MATERIALS TRANSACTIONS
New Arrival Alert : OFF

You can use this feature after you logged into the site.
Please click the button below.

Log in / Sign up
ONLINE ISSN: 1347-5320
PRINT ISSN: 1345-9678

MATERIALS TRANSACTIONS Vol. 58 (2017), No. 4

  • Microstructures and Charge-Discharging Properties of Selective Laser Sintering Applied to the Anode of Magnesium Matrix

    pp. 525-529

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016415

    Selective laser sintering (SLS) is an additive manufacturing (3D printing) technique that can be applied to the anode of lithium batteries to simplify the manufacturing process and enhance the production efficiency. The specific surface nanostructures and intermetallic compounds (IMC) induced by the SLS process can improve the capacity and cycle life. In this study, a stable anode for a lithium ion battery was successfully fabricated by the SLS process, the capacity of the battery exceeded 150 mAhg−1 after 10 cycles under a 0.1 C current rate at room temperature. Moreover, the capacity enhanced to 250 mAhg−1 after 10 cycles under a 0.1 C current rate at the high temperature of 55℃. The results show the potential of the SLS technique for application in the lithium ion battery industry.
  • Adoption of Hybrid Dicing Technique to Minimize Sawing-Induced Damage during Semiconductor Wafer Separation

    pp. 530-534

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016366

    This article demonstrates that the chipping damage resulting from silicon wafer separation can be more effectively suppressed by the adoption of hybrid dicing (a duel process that uses laser ablation prior to mechanical sawing) than single dicing, such as sawing. This work shows that the adoption of the hybrid dicing technique induces sacrificial fracture at the laser-induced groove tip to save the regions outside of the groove formed along the scribe region of the wafer. Particularly, this study details how a pre-existing groove (i.e., a laser-induced groove) on the front surface of the wafer interacts with the saw blade penetration-induced trench during the second step of the hybrid dicing process. According to the experimental results, the magnitude of the chipping damage in the chips diced from a wafer including a laser-induced groove with a larger aspect ratio was more effectively reduced at a more rapid sawing velocity. However, since a laser-induced groove with a larger aspect ratio could also have a bigger curvature in its tip, adopting a groove with the optimum shape was necessary for effective prevention of dicing-induced damage during hybrid dicing.
  • Dissolution Characteristic of Titanium Oxycarbide Electrolysis

    pp. 535-538

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.MK201616

    Aiming at the problems of residual anode and free carbon generated in titanium oxycarbide electrolysis (TiC0.5O0.5), the phase composition and microstructure of TiC0.5O0.5 were characterized by XRD, SEM, EDS and POM. The results show that: titanium oxycarbide (TiC0.5O0.5) with similar crystal morphology and structure could be obtained by carbothermic reduction from TiO2 and sintering from TiC and TiO, which is composed of 15~21% gray-white titanium carbide, 56~69% yellow titanium oxycarbide and 13~25% aubergine titanium oxycarbide. The grain color of titanium oxycarbide is related to the content of carbon and oxygen. Gray-white titanium carbide contains 20~30% C, yellow titanium oxycarbide 10~50% C and 10~20% O, and aubergine titanium oxycarbide 5~10%C and 25~30% O. The structure of titanium oxycarbide is not uniformity, which results in the formation of residual anode and carbon. The gray-white and aubergine components in titanium oxycarbide are rich in TiC and TiO respectively, which generate free C, CO2, Ti2O3 and TiO2 after electrolysis.
    x

    Readers Who Read This Article Also Read

    1. Revisit of Rule-Deletion Strategy for XCSAM Classifier System on Classification Transactions of the Institute of Systems, Control and Information Engineers Vol.30(2017), No.7
    2. One-Pot Fabrication of Hydrophobic Nanocellulose-Silica Film for Water Resistant Packaging Application Journal of the Japan Institute of Energy Vol.96(2017), No.8
    3. Mixed Meal Model in Type 1 Diabetes Transactions of the Institute of Systems, Control and Information Engineers Vol.30(2017), No.7
  • In-Plane Positional Fluctuations of Zinc Atoms in Single Crystal Mg85Zn6Y9 Alloy Studied by X-ray Fluorescence Holography

    pp. 539-542

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016459

    We performed X-ray fluorescence holography measurements on a single crystal Mg85Zn6Y9 alloy, having a synchronized 18R long period stacking ordered structure, and successfully obtained Zn Kα holograms. The reconstruction shows “U”-shaped atomic images in remarkable contrast to the prediction of an existing model with Zn6Y8 L12 clusters. To explain this feature we calculated holograms using a model with positional fluctuations, and fit the reconstruction to the experimental results. It was found that large rotational fluctuations of the clusters can explain the “U”-shaped images.
  • Stress Corrosion Behavior of Mg–2 mass% Sn Alloy by Equal-Channel Angular Extrusion

    pp. 543-548

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.L-M2017806

    In this work, the stress corrosion behavior of Mg–2 mass% Sn alloy in simulated body fluid solution was systematically investigated to determine its performance in a physiological environment. The effect of equal-channel angular extrusion (ECAE) on stress corrosion behavior of Mg–2 mass% Sn alloy was investigated using three-point bending test. ECAE process changed both grain size and Mg2Sn second phase distribution. The average grain size under homogenization annealing condition (about 123.61 μm) was significantly reduced to 34.32 μm after four ECAE passes. Mg2Sn phase formed more uniformly both in the grains and along the grain boundaries with ECAE process. The average volume fraction of Mg2Sn phase increased with increasing passes. The microstructure became more homogeneous with further ECAE passes. In bent-beam stress corrosion test, the average crack depths of samples underwent ECAE process were significantly lower than that of sample under homogenization annealing condition. This showed that the ECAE process could reduce crack propagation rate. The enhancement of stress corrosion resistance is attributable to uniform second phase distribution and grain refinement via ECAE process.
  • Effect of Trace Cu on Microstructure, Spreadability and Oxidation Resistance Property of Sn-xCu Solders

    pp. 549-553

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.MA201609

    Sn-xCu (x = 0.5, 0.7, 0.9, 1.1, 1.3) solders were prepared to investigate the influence of trace Cu on the microstructure, the spreadability and the oxidation resistance property of Sn-xCu lead-free solder. Researches have shown that the Cu content had a significant impact on the microstructure, the microstructure of Sn-0.7Cu solder was almost fine dendrites and others were composed of coarser dendrites. The liquidus temperatures of Sn-xCu were around 227℃, the peak of solidification temperature had vast difference and the biggest difference was 8.8℃. The peak of solidification temperature of Sn-0.7Cu was the smallest, with 192℃. The spreading rate of Sn-xCu solders greatly improved, in which Sn-0.5Cu improves by nearly 4 percents, Sn-0.7Cu improves by nearly 3 percents and the others improve by 2 percents around from 260℃ to 290℃. With the increase of Cu content, there were no obvious changes to solder with wetting power and wetting time, interfacial IMC thickness of Sn-xCu/Cu solders. The color of oxidation film deepened due to the serious oxidation with the increase of the temperature. The oxide slag of Sn-xCu solders decreased and then increased with the increase of Cu content, in which the oxide slag of Sn-0.7Cu solder was the lowest, about 18.5% of Sn-0.5Cu and 38% of Sn-1.3Cu.
  • Temperature Dependency of Diffusional Transformation Texture Development in Steel Sheet

    pp. 554-560

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016393

    The temperature dependency of diffusional transformation texture development in steel sheet was investigated by electron backscatter diffraction. The site of the precipitated pro-eutectoid ferrite (PF) grains and the orientation relation with the surrounding austenite (γ) phase were affected by the transformation temperature. The PF on the triple junction, which has a Kurdjumov-Sachs relation (K-S) with the two surrounding γ phases (double K-S [DKS] relation) with high probability, predominated in the high-temperature transformation, whereas the PF on the grain boundary, which fulfills DKS with lower probability than the PF on triple junction, became predominant with decreasing temperature. The intensity of the variant selection on transformation decreased with decreasing transformation temperature. The texture predicted by the DKS model reproduced the measured PF texture, indicating that the intensity of the variant selection obeying DKS decreased with decreasing transformation temperature. Therefore, the intensity of the variant selection was affected by the degree of supercooling. The DKS rule operates strongly on the transformation in the high-temperature region, corresponding to a low degree of supercooling. However, the DKS rule has a small effect when the temperature decrease corresponds to a high degree of supercooling.
  • Experimental Observation on Solid-State Reactive Diffusion between Sn–Ag Alloys and Ni

    pp. 561-566

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016409

    The kinetics of the solid-state reactive diffusion between Sn–Ag alloys and pure Ni was experimentally observed to examine effects of addition of Ag into Sn on the growth behavior of compound at the interconnection between the Sn-base solder and the multilayer Au/Ni/Cu conductor during energization heating. In this experiment, sandwich (Sn–Ag)/Ni/(Sn–Ag) diffusion couples with Ag concentrations of y = 0.011–0.033 were prepared by a diffusion bonding technique, and then isothermally annealed at temperatures of T = 453–473 K for various periods up to 3169 h, where y is the mol fraction of Ag. After annealing, an intermetallic layer consisting of Ni3Sn4 was recognized between the Sn–Ag and Ni specimens in the diffusion couple. Here, the concentration of Ag in Ni3Sn4 is negligible. The mean thickness of the intermetallic layer is proportional to a power function of the annealing time, and the exponent of the power function takes values of 0.33–0.43 at T = 453 K and those of 0.54–0.62 at T = 473 K. Thus, the growth of the intermetallic layer is controlled by boundary and volume diffusion at T = 453 K. In contrast, at T = 473 K, interface reaction and interdiffusion contribute to the rate-controlling process of the intermetallic growth. The addition of Ag into Sn accelerates the intermetallic growth within the experimental annealing times.
  • Kinetics of Reactive Diffusion in the Co/Zn System at Solid-State Temperatures

    pp. 567-573

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016416

    The kinetics of reactive diffusion in the Co/Zn system was experimentally examined at solid-state temperatures. In this experiment, sandwich Zn/Co/Zn diffusion couples were prepared by a diffusion bonding technique, and then isothermally annealed in the temperature range of 523–573 K for various times up to 211 h. Owing to annealing, an intermetallic layer consisting of the γ, γ1 and γ2 phases was formed at the original interface in the diffusion couple, where the thickness is much smaller for the γ and γ1 phases than for the γ2 phase. Thus, the γ2 phase predominantly governs the overall growth of the intermetallic layer. The total thickness of the intermetallic layer increases in proportion to a power function of the annealing time. The exponent of the power function takes values of 0.54–0.56 at 523–548 K and that of 0.85 at 573 K. Consequently, volume diffusion mainly controls the layer growth at 523–548 K, but interface reaction as well as volume diffusion contributes to the rate-controlling process at 573 K.
  • Early-Stage Recrystallized Grains in Copper Single Crystals Deformed in Tension along <111> Direction

    pp. 574-579

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016455

    The objective of the present study was to characterize early-stage recrystallization in copper single crystals. Two crystals with different front surfaces, i.e., {110} or {112}, were deformed in tension along the <111> direction to a tensile strain of 0.2. The deformation was uniform without deformation bands. Thin disk specimens prepared from the deformed <111>{110} and <111>{112} crystals were heated in a high vacuum to a set temperature with a holding time of 10 s, and subsequently observed. This process was repeated by raising the heating temperature for each step until the first detection of recrystallized grains. In all specimens, recrystallization was found after annealing at almost the same temperature, about half of the melting point in the absolute temperature scale. Each recrystallization aggregate was composed of a pair of major recrystallized grains with a coherent twin boundary. Small annealing twins were detected inside the larger recrystallized grains but not in the smaller grains. The present results suggest that recrystallization in copper begins with the formation of pairs of twin-related recrystallized grains, followed by the introduction of annealing twins.
  • Ion-Irradiation Effect on Strain Rate Sensitivity of Nanoindentation Hardness of W Single Crystal

    pp. 580-586

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.ML201603

    The local strain rate (LSR) dependence of nanoindentation (NI) hardness was investigated by using standard constant strain rate (CSR) test method and strain rate jump (SRJ) test method for W single crystal with the surface orientation of {001} before and after 6.4 MeV Fe3+ irradiations (nominal damage level of 0.1, 1 and 2 dpa, 573 K). The effect of ion-irradiation on the LSR sensitivity of NI-hardness at room temperature (RT) was evaluated by changing LSR between 0.3 s−1 and 0.01 s−1 or 0.03 s−1 and 0.001 s−1. Under these experimental conditions, ion-irradiation increases NI-hardness and slightly decreases LSR sensitivity of NI-hardness for all damage levels. The effect is more pronounced with increasing damage level. The LSR sensitivity values are ranging between 0.015 and 0.04 in SRJ tests, and between 0.0425 and 0.06 in CSR tests, indicating that the deformation of bcc W{001} at RT is controlled by a high lattice friction stress. The decrease in LSR sensitivity by ion-irradiation could be attributed to the increase in the athermal stress caused by ion-irradiation induced defect structures, which is reflected to a decrease in the activation volume of dislocation motion in ion-irradiated W{001}.
  • Activation Stress for Slip Systems of Pure Magnesium Single Crystals in Pure Shear Test

    pp. 587-591

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016402

    With a hexagonal close packed structure, magnesium has many slip systems. Pure shear tests were carried out to evaluate their critical resolved shear stresses (CRSS). As a result, the CRSS for the basal slip was 0.7 MPa, and it was close to conventional values. When the shear stress of 40 MPa was applied in parallel to the prismatic plane, the {1012} twin deformation occurred only, and the prismatic slip deformation did not occur. This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 80 (2016) 334–339.
  • Atmosphere Gas Carburizing for Improved Wear Resistance of Pure Titanium Fabricated by Additive Manufacturing

    pp. 592-595

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016361

    In order to improve wear resistance of pure titanium fabricated by additive manufacturing, its surface was hardened by atmosphere gas carburizing. For the study, the pure titanium was fabricated by electron beam melting system. The microstructures and wear properties of the as-built and carburized titanium were investigated. After carburizing, hardness was increased and titanium carbides were precipitated in the surface region. The friction coefficients of the both specimens were estimated by dry sliding friction tests; the friction coefficient of carburized titanium is lower than that of as-built titanium. The improvement of wear property would be a result of high surface hardness and the slippery nature of titanium carbide formed on the surface.
  • Mass Production and Particle Characterization of Fine Spherical Ag Powder by Gas Combustion-Type Spray Pyrolysis

    pp. 596-599

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.Y-M2017804

    A large-scale spray pyrolysis apparatus in which the mist is pyrolyzed by a flame using a gas burner was developed for the mass production of Ag powder. Forty ultrasonic vibrators with a frequency of 1.6 MHz generated 4 dm3/h of mist. The thermal stability of the ultrasonic vibrators was improved using water-cooling. Spherical Ag powder was continuously produced, and the yield of the powders remained above 95% over 60 hours of continuous production with starting solution concentrations of up to 1.5 mol/dm3. Scanning electron microscopy (SEM) analysis showed that the particles were sub-micrometer in size with a dense microstructure, and they did not aggregate. Powder X-ray diffraction (XRD) demonstrated that the as-prepared Ag powder exhibited high crystallinity. The particle size of the Ag powder was approximately in agreement with the predicted size, calculated under the assumption that one Ag particle was formed from one droplet of mist. Moreover, 7 kg of Ag powder was produced over 12 h at 1.5 mol/dm3. This apparatus exhibited good reliability for the continuous mass production of Ag powder.
  • Effect of Heating Conditions on Surface Modification of Titanium with a Mixture of Iron, Graphite and Alumina Powders

    pp. 600-605

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016294

    We developed a new surface modification technique called “iron-powder pack (IPP) treatment”. A layer of titanium carbonitride, Ti(C, N), was formed on the surface of a titanium sample embedded in a mixture of iron, graphite, and alumina powders and held around 1273 K in a nitrogen flow. In this work, IPP treatment using a 4:6:3 (volume ratio) mixture of iron, graphite, and alumina powders was applied to titanium plates, and the effects of the heating temperature and nitrogen gas flow rate on the microstructures near the titanium surface were investigated. The Ti(C, N) layer was observed on the titanium plate heat-treated at 1173 K for 3.6 ks at a nitrogen flow rate of 0.5 L/min. This layer became uniform and thick as the heating temperature increased. At 1373 K, a Ti(C, N) layer with a thickness of more than 30 μm that increased the hardness of the titanium surface to an HV value of about 1500 was obtained. In addition, an increase in the nitrogen flow rate increased the surface hardness further. Spherical titanium powder was treated at 1273 K to examine the growth of the Ti(C, N) layer. The layer thickness increased with the holding time. Because the average diameter of the spherical powder was unchanged after heating, the Ti(C, N) layer grew toward the inside of the titanium via the diffusion of carbon and nitrogen from the powder mixture and the atmosphere.
  • Effect of Dissolved Impurities on the Lightness and Surface Morphology of Nickel Deposits from Chloride Electrowinning Solutions

    pp. 606-612

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016442

    This study investigated the effect of dissolved impurities on the lightness, surface morphology, and current efficiency of deposited nickel during electrowinning. Nickel electrodeposition was performed at a current density of 300 A·m−2 and 7.2 × 105 C·m−2 of charge in an unagitated chloride solution containing Mn2+, Cr3+, and SO42− ion impurities with a pH from 1 to 3, at a temperature of 333 K. Solutions containing 10 g·dm−3 of Mn2+ resulted in a slight decrease in current efficiency for nickel deposition and smaller crystal sizes in the deposited nickel. The lightness of deposited nickel decreased for Mn2+ concentrations exceeding 1 g·dm−3. When nickel deposition was performed using a soluble nickel anode to prevent the formation of MnO2 at the anode, greater nickel lightness resulted than with an insoluble anode, suggesting that MnO2 produced by the insoluble anode caused decreased lightness of nickel. In solutions containing Cr3+, the current efficiency of nickel gradually decreased with increasing Cr3+ concentrations and significantly decreased at Cr3+ concentrations above 0.1 g·dm−3. The lightness of deposited Ni greatly decreased with increasing concentrations of Cr3+ above 0.001 g·dm−3. Formation of Cr(OH)3 at the cathode layer is presumed to suppress nickel deposition, resulting in some codeposition of NiO and Ni(OH)2 along with Ni, which causes the nickel current efficiency and lightness to decrease. Conversely, solutions containing SO42− resulted in a moderate decrease in nickel current efficiency at SO42− concentrations above 50 g·dm−3 and a significant decrease above 100 g·dm−3. The lightness of deposited nickel increased slightly at SO42− concentrations of 20 g·dm−3 and strongly increased above 20 g·dm−3. Because the overpotential for nickel deposition increases with the concentration of SO42−, the surface of the deposited nickel becomes smooth, resulting in greater lightness. This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 80 (2016) 539–545.
  • Removal of Oxygen in Ti–Si Melts by Arc-Melting

    pp. 613-618

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2017003

    Oxygen removal from Ti–Si melts (Si: 9.1–30 mass%) during arc melting was investigated. High-purity Si was added to either Ti with a high oxygen content (High O Ti, O: 1.6 mass%) or commercially pure Ti (CP Ti, O: 0.104 mass%) melted under Ar or He gas flow conditions at atmospheric pressure. At Si additions of 23 mass% and 30 mass%, the oxygen content of the Ti–Si ingots decreased. After melting, Si and amorphous SiO2 powders were observed in the chamber, which suggested that the oxygen in the melts was removed in the form of SiO gas. The oxygen content of the Ti–Si ingots after melting varied as a function of position within the ingot; the residual oxygen content was lowest in the top section of the ingots and highest in the bottom section. Under the Ar gas flow, the oxygen content of the High O Ti–30Si ingot decreased to 0.136 mass% and 0.609 mass% in the top and center sections of the ingot, respectively; similarly, the oxygen content of the CP Ti–30Si ingot decreased to 0.030 mass% and 0.051 mass% in the top and center sections, respectively. After melting under He gas flow, the oxygen contents of the CP Ti–30Si ingot in the top, center, and bottom sections were 0.020 mass%, 0.021 mass%, and 0.029 mass%, respectively. Better uniformity of oxygen distribution in the ingots was achieved under the He gas flow than under the Ar gas flow because the melted region is extended in the depth direction by using He gas. During melting, no significant evaporation of Ti and Si occurred, which is an advantage of arc melting that operates at atmospheric pressure over electron beam melting that occurs in vacuum.
  • Chromium-Based Duplex Alloy for Wear and Corrosion Resistant Cladding

    pp. 619-622

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016339

    A chromium-based duplex alloy is proposed for a novel class of alloys for hot and harsh environments. The alloy is defined as a duplex microstructure comprised of a hard and high-strength chromium-based BCC (α) phase and a ductile FCC (γ) phase to overcome the brittleness of the conventional α-Cr alloy. The candidate composition of the alloy was selected from a Cr-Fe-Ni ternary system, and the mechanical properties were evaluated. The abrasion and corrosion properties of a surface-remelted chromium-based duplex alloy were compared with those of a Co-based cladding alloy (Bishilite® No. 6), and the results suggested its potential use as a wear and corrosion resistant cladding.
  • Influence of Dog-Bone Width on End Profile in Plan View Pattern Control Method in Plate Rolling

    pp. 623-628

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.P-M2017805

    A plan view pattern control method for plate rolling called the Mizushima Automatic Plan View Pattern Control System (MAS) or Dog Bone Rolling (DBR) was developed. In this method, the slab is given a non-uniform thickness profile in the width direction to obtain non-uniform elongation at following flat rolling. In order to make the plate more rectangular under various rolling conditions, prediction of elongation at following flat rolling is necessary. In this research, the influence of the width of the dog-bone (overly thick part at the slab width edge) on the fish-tail length (over-elongation at the slab end) is investigated. The fish-tail length increases as the dog-bone width increases and the dog-bone width ratio decreases. These phenomena are related to the following behavior of the restriction of excessive elongation in the dog-bone because of existence of unrolled volume before roll gap entrance: As the dog-bone width increases and the dog-bone width ratio decreases, the working length of restricting stress increases. Hence, restricting stress is released earlier and the rolling length for fish-tail formation increases. As a result, the fish-tail length increases. Therefore, in prediction of the plan view pattern, not only the dog-bone thickness, but also the dog-bone width and dog-bone width ratio should be considered. This Paper was Originally Published in Japanese in J. JSTP 57 (2016) 347–352.
  • Accurate Evaluation of Copper Alloy Fluidity Using Automatic Pouring Equipment with Improved Pouring Cup Heat Insulation

    pp. 629-634

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.F-M2017802

    New pouring equipment was developed for the measurement of copper alloy fluidity. The fundamental characteristics of the developed equipment are the pouring cup system, which has high heat-retention, a stopper system without preheating, and a pouring temperature determination system. In the evaluation of the developed device, the temperature of the molten copper alloy was decreased by 30 K from pouring to the stability of the measurement of the molten alloy temperature in the pouring cup. The rate of temperature decrease of the molten copper alloy in the pouring cup until the pouring temperature was 3.5 K/s. Experimentally obtained results demonstrated that the linearity between the superheat above liquidus temperature and flow length improved compared with that reported from earlier studies. The standard deviation of flow length in the equipment was 20 mm. These results indicate that the effect of the casting conditions on flow length of the copper alloys will be evaluated accurately with the developed equipment. This Paper was Originally Published in Japanese in J. JFS 87 (2015) 855–860.
  • Effect of Coat Permeability on Mold Filling in Expendable Pattern Casting Process of Thin Wall Aluminum Alloy Casting

    pp. 635-640

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.F-M2017803

    The effect of coat permeability on mold filling for thin wall aluminum alloy castings in the expendable pattern casting (EPC) process was investigated experimentally. Thin wall aluminum alloy plates were cast by the EPC process, using eight kinds of coats with different permeabilities. The fluidity length and melt velocity were measured. The use of thin expendable polystyrene (EPS) pattern led to shorter fluidity length of melt. When the coat permeability was less than approximately 2, the fluidity length of the melt and melt velocity increased with increasing coat permeability. When the coat permeability was greater than approximately 2, even when the coat permeability increased, the fluidity length of the melt and melt velocity did not increase so much. The application of high expansion ratio of EPS pattern or high pouring temperature, led to long fluidity length of the melt. The distances of melt flow stop were predicted based on the heat transfer from the molten metal to the mold through the coat using measurement melt velocity values. The predicted values more or less agreed with experimental values for fluidity length. This Paper was Originally Published in Japanese in J. JFS 88 (2016) 192–197.
  • An Electromagnetic Helmholtz-Coil Probe for Arbitrary Orientation Crack Detection on the Surface of Pipeline

    pp. 641-645

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016419

    Subjected to hoop stress and land movement load, the orientation of cracks on the surface of pipeline may be axial direction, circumferential direction or the others. In this paper, an electromagnetic Helmholtz-coil probe is presented to detect the oriented cracks on the surface of pipeline. A structure of equal-spaced TMR sensor array of the Helmholtz-coil probe is applied to scan the full circumference of the pipeline simultaneously in a single pass. The simulation and experiment results indicate that using the combination effect of the electric current perturbation and the magnetic flux leakage, the oriented crack can be mapped clearly.
  • Stress-Enhanced Transformations from Hypothetical B2 to Stable L10 and Amorphous to fcc Phases in Fe50Ni50 Binary Alloy by Molecular Dynamic Simulations

    pp. 646-654

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016162

    Molecular dynamics (MD) simulations were performed for an Fe50Ni50 (at.%) alloy with NTp ensemble to keep the number of atoms (N), temperature (T = 673 K), and pressure (p ∼ 101.325 kPa) constant under a GrujicicZhou-type MD potential from an Embedded Atom Method scheme with a cut-off distance of 1 nm. An Fe50Ni50 alloy was initially created as a hypothetical chemically-ordered B2 structure with a 12 × 12 × 12 supercell comprising 3456 atoms. Subsequently, it was annealed at 673 K, without the application of stress, and then under a uniaxial tension of ∼290 MPa, and shear stresses of ∼570 and ∼2940 MPa. The results revealed that stress contributed to a change in the transformation scheme to the L10 phase from partially to fully of the system with a reduction of time. On the other hand, an as-quenched amorphous phase under a shear stress of ∼680 MPa, transformed to a disordered fcc-derivative phase. Therefore it is clear that stresses in MD simulations play a crucial role in enhancing the atomic motion during a transformation.
  • Effect of Molybdenum Content on Heat Treatment Behavior of Multi-Alloyed White Cast Iron

    pp. 655-662

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016396

    The effect of the Molybdenum (Mo) content on the heat treatment behavior of multi-alloyed white cast iron was investigated. The cast iron with varying Mo contents from 0.12 to 7.66% under the basic alloy composition of 5% Cr, W and V each was prepared. After annealing at 1223 K for 18 ks, the test specimens were austenitized at 1373 K for 3.6 ks in a vacuum furnace and subsequently hardened by a jet-spray of liquid nitrogen. The tempering was carried out at temperatures from 673 to 873 K at 50 K intervals for 12 ks. It was found that the hardness in the as-hardened state was increased progressively with an increase in the Mo content. The volume fraction of the retained austenite (Vγ) decreased markedly when the Mo content was increased over 1.17%. In the tempered state, the hardness curve showed clear secondary hardening due to the precipitation of fine secondary carbides and a reduction of the Vγ. The Vγ value in each specimen decreased gradually as the tempering temperature was elevated, but reduced greatly when tempered at 748 to 823 K. The maximum tempered hardness (HTmax) was obtained in the specimen tempered at 798 K where the Vγ was less than 10%. The HTmax increased first, and then subsequently decreased with an increase in the Mo content. The highest HTmax value, 946 HV30, was obtained in the specimen with 4.98%Mo. It was found that the 15–37%Vγ in the as-hardened state was necessary to get the hardness over 900 HV30 by tempering. The degree of secondary hardening (ΔHs) increased as the Mo content rose from 0.12 to 4.98% where the difference between the Vγ in the as-hardened state and that at HTmax (ΔVγ) was 22–23%.
  • Induction Brazing of 304 Stainless Steel with a Metalloid-Free Ni-Zr-Ti-Al-Sn Amorphous Foil

    pp. 663-667

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016319

    The feasibility of a novel metalloid-free Ni57Zr20Ti17Al5Sn1 (at.%) amorphous filler metal for 304 SS brazing was investigated by induction brazing. The joining process can be completed within seconds in argon atmosphere due to the sensitive response of induction heating. The effects of joining time on the microstructure of joints and the joint shear strength were investigated. The results indicate that the joints brazed for 5 s and 10 s exhibit good wetting between the base metal and the filler metal. Overheating occurred due to skin effect for the holding time of 20 s. The brazed seam of 5 s is composed of Ni-rich phases while the brazed seam of 10 s is composed of Fe-rich phases indicating the gradual homogenization of the bonding region with the base metal as a function of holding time. Shear strength of as high as 235 MPa was obtained when brazed for 10 s.
  • Influence of Structure on Thermal Conductivity of Insulation Board Used during Ingot Casting

    pp. 668-672

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016372

    In order to improve heat prevention property of insulation board used in hot top during casting of steel ingot, thermal conductivities of insulation boards of solid structure and porous structure with different porosities were investigated using numerical simulation and calorimetric techniques. A heat transfer model used to calculate the thermal conductivity of insulation boards was developed, and the accuracy of the model was verified by calorimetric experiment. A series of porous insulation boards made of floating beads with different porosities were designed and effect of porosity on thermal conductivity of porous insulation board was investigated by numerical simulation. It was found that porous insulation board performs a better heat prevention property than insulation board of solid structure. Thermal conductivity of porous insulation board decreases notably with the increase of porosity. By contrast, the sizes of pores almost have no influence on the thermal conductivity of porous insulation board.
  • Fabrication of Vapor-Grown Carbon Fiber-Reinforced Magnesium-Calcium Alloy Composites by Compo-Casting Process

    pp. 673-678

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.MBW201607

    Magnesium-calcium alloy composites reinforced with nickel-coated vapor-grown carbon fibers (VGCFs) were fabricated using a compo-casting process. Then, the microstructures and mechanical properties of these composites were investigated. The Mg-5Al-3Ca (AX53) alloy exhibited a dendritic microstructure with a coarse lamellar (Mg, Al)2Ca phase along the grain boundaries instead of the irregular β-Mg17Al12 phase found in the Mg-5Al alloy. For the 0.5% Ni-coated VGCF-reinforced AX53 alloy composite, the VGCFs were well dispersed in the matrix, with the nickel coating diffused into the metal. Al3Ni compounds formed both inside the grains and on the grain boundaries. The ultimate tensile strength (UTS) and strain-hardening of the AX53 alloy, in comparison with the Mg-5Al alloy, were improved significantly to the point of fracture. Furthermore, an increase in the UTS of the composite was achieved with the addition of 0.5% VGCFs, along with an increase in the total elongation, which could mainly be attributed to the strain hardening during a larger strain. The 0.2% yield stress was slightly improved as a result of the small amount of introduced Ni-coated VGCFs. However, the elongation dropped for the 1.0% VGCF-reinforced AX53 alloy composites, which led to a low strength similar with that of the AX53 alloy.
  • Critical Current and n-Value of Heterogeneously Cracked Superconducting Tapes, Studied by a Monte Carlo Simulation Method Combined with a Model of Current Shunting at Cracks

    pp. 679-687

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.MBW201602

    Influences of crack size-distribution and specimen length on the critical current and n-value of heterogeneously cracked superconducting tapes were studied by a Monte Carlo simulation method combined with a model of crack-induced current shunting. In simulation, model specimens, constituted of a series of sections having cracks with different size to each other, were used. It was shown by the present simulation that (i) both of the critical current and n-value decrease with increasing width of crack size distribution, (ii) n-value decreases more sensitively to the increase in width of crack size distribution in comparison with the critical current, and (iii) the features (i) and (ii) stated above are enhanced with increasing specimen length. Also, the experimentally observed feature that the width of distribution of critical current decreases with increasing length in heterogeneously cracked superconducting tapes was realized by the present simulation. This result was in good accordance with the reported feature that local information of critical current values in a specimen is diluted when the voltage tap distance is large.
  • Pyrometallurgical Recovery of Gallium from GaN Semiconductor through Chlorination Process Utilizing Ammonium Chloride

    pp. 688-691

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016395

    Pyrometallurgical chlorination process has been examined for the recovery of gallium from gallium nitride, GaN, a promising semiconductor material. It was found that gallium was successfully recovered as volatile gallium chloride by thermal treatment of GaN powder in the presence of ammonium chloride. All gallium could be recovered as volatile species at 500℃. The results indicate that gallium can be extracted from complex mixture of semiconductor materials or wastes through this process. The influence of reaction conditions, such as reaction temperature and composition of ammonium chloride, was examined.
  • Demonstration of the Applicability of Nondestructive Microwave Testing to the Long-Range Inspection of Inner-Surface Cracks in Tubes

    pp. 692-696

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2017008

    This study evaluated the applicability of nondestructive microwave testing method for the long-range detection of inner-surface cracks in metallic tubes. Two seamless straight tubes 7 m in length and 23.0 mm in inner diameter were prepared, and artificial circumferential slits penetrating the tube walls were introduced. A probe to propagate microwave inside the tube, designed based on three-dimensional finite element simulations, was attached to an end of the tube, and the reflections of the microwave propagating inside the tube were measured using a network analyzer. The experiments confirmed clear reflections due to the slits situated 6 m away from the probe. Furthermore, imposing a signal processing method to compensate for the dispersion of the microwave clarified the reflections and enabled the slit to be localized quantitatively from the time-of-flight of the reflections.
  • Phase Transformation Induced by High Nitrogen Content Solid Solution in the Martensitic Stainless Steels

    pp. 697-700

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2016418

    A high density plasma nitriding experiment was performed on a circular disk specimen of martensitic stainless steel at the temperature of 673 K for 14.4 ks. The nitrided thickness was 80 μm in depth from the surface with a high surface nitrogen concentration of 31 at%. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) and, electron backscattering diffraction (EBSD) were used to analyze the microstructure, the nitrogen content distribution, the phase formation, the grain size, and the straining in the specimen. Phase transformation from martensitic to austenitic phases took place together with high straining as well as grain size refinement.
  • New Type Fe-Mn Based Alloys with Super Elinvar and Invar Characteristics

    pp. 701-704

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2320/matertrans.M2017027

    In the present study, both excellent Elinvar and Invar characteristics have been found in the antiferromagnetic Fe-Mn based alloys consisting of about 25 mass%Mn and a small amount of Mo, W, Nb, Ta, Ti, Zr and Hf which are belonging to the 4~6 families in the periodic table. The best characteristics obtained in the present study were constant Young's modulus (Elinvar characteristics) of 1 × 10−6 K−1 and a small thermal expansion coefficient (Invar characteristics) of 8 × 10−6 K−1 in the temperature range of 293~353 K under appropriate treatment of cold working and annealing. Such alloys will be expected as applications in a wide field such as precision instruments, electromagnetic devices and controlling devices.

Article Access Ranking

25 Mar. (Last 30 Days)

  1. Dependence of Carbon Concentration and Alloying Elements on the Stability of Iron Carbides ISIJ International Advance Publication
  2. Comprehensive Optimization Control Technology of Rolling Energy and Oil Consumption in Double Cold Rolling ISIJ International Advance Publication
  3. Experiments on Removal of Hydrophilic Fine Particles in Bubbly Flow ISIJ International Vol.59(2019), No.2
  4. Effects of Impurities and Processing Conditions in Al–1%Mn Alloys on the Formation of Thermally Stabilized Substructures MATERIALS TRANSACTIONS Vol.59(2018), No.11
  5. Temperature Field Distribution of a Dissected Blast Furnace ISIJ International Advance Publication
  6. Coating Film Profiles Generated by Fluctuating Location of the Wiping Pressure and Shear Stress ISIJ International Vol.59(2019), No.2
  7. Effect of EAF Slag Temperature and Composition on its Electrical Conductivity ISIJ International Vol.59(2019), No.2
  8. Fundamentals of Silico-Ferrite of Calcium and Aluminium (SFCA) Iron Ore Sinter Bonding Phase Formation: Effects of Basicity and Magnesium on Crystallisation during Cooling ISIJ International Vol.59(2019), No.2
  9. Evolution of Blast Furnace Process toward Reductant Flexibility and Carbon Dioxide Mitigation in Steel Works ISIJ International Vol.56(2016), No.10
  10. Structure Based Viscosity Model for Aluminosilicate Slag ISIJ International Advance Publication

Search Phrase Ranking

25 Mar. (Last 30 Days)

  1. blast furnace
  2. blast furnace productivity
  3. blast furnace permeability
  4. galvanizing
  5. tuyere abrasion
  6. tuyere erosion
  7. tuyere failure
  8. lme
  9. wear on tuyere
  10. 鉄と鋼