Steel Science Portal

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. 54 (2013), No. 1

  • Improvement in Mechanical Properties of a Cu–2.0 mass%Ni–0.5 mass%Si–0.1 mass%Zr Alloy by Combining Both Accumulative Roll-Bonding and Cryo-Rolling with Aging

    Yusaku Takagawa, Yukinaru Tsujiuchi, Chihiro Watanabe, Ryoichi Monzen, Nobuhiro Tsuji

    pp. 1-8

    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.M2012207

    Abstract

    The enhancement in tensile properties of a Cu–2.0 mass%Ni–0.5 mass%Si–0.1 mass%Zr alloy without reducing its electrical conductivity is attempted by combining both accumulative roll-bonding (ARB) and cryo-rolling with aging treatment. The grain sizes of the alloy pre-aged at 450°C and ARB-processed in six cycles (P-ARB) and of the alloy pre-aged at 450°C and cryo-rolled to a 90% reduction (P-90CR) are refined to about 0.1 and 0.2 µm, respectively. Both six cycles of ARB and 90% cryo-rolling, together with the presence of fine precipitates formed by pre-aging at 450°C, give significant grain refinement. The P-90CR alloy aged at 350°C exhibits a higher 0.2% proof stress of 830 MPa and a higher tensile strength of σu = 900 MPa than the P-ARB alloy aged at 375°C. The aged P-90CR alloy exhibits almost the same elongation of 6% up to failure and the same electrical conductivity of σ = 45% IACS as the aged P-ARB alloy. The higher proof stress of the aged P-90CR alloy than the aged P-ARB alloy is ascribed to the higher dislocation density in the aged P-90CR alloy. The value of σu = 900 MPa for the aged P-90CR alloy is larger than that of σu ≈ 830 MPa for conventional commercial Cu–3.0 mass%Ni–0.65 mass%Si system alloys. The value of σ for the former alloy is nearly identical to σ ≈ 46% IACS for the latter alloys.

  • Magnetic Field-Induced Transition in Co-Doped Ni41Co9Mn31.5Ga18.5 Heusler Alloy

    Takuo Sakon, Kenta Sasaki, Daisuke Numakura, Michihito Abe, Hiroyuki Nojiri, Yoshiya Adachi, Takeshi Kanomata

    pp. 9-13

    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.M2012289

    Abstract

    Thermal strain, magnetostriction and magnetization measurements of Ni41Co9Mn31.5Ga18.5 polycrystalline ferromagnetic shape memory alloy (FSMA) were performed across the martensitic transition temperature, TM, and the reverse martensitic transition temperature, TR, at atmospheric pressure. When cooling from the austenite phase, a steep decrease in thermal expansion due to the martensitic transition at TM was found. When heating from the martensitic phase, a steep increase in the thermal expansion due to the reverse martensitic transition at TR was observed. These transition temperatures decreased gradually with increasing magnetic field. The field dependence of the martensitic transition temperature, dTM/dB, is −4.2 K/T and that of the reverse martensitic transition temperature, dTR/dB, is −7.9 K/T. The metamagnetic transition appeared between 330 and 390 K. The results of thermal strain and magnetization measurements indicate that a magneto-structural transition occurred at TM. The region above TM or TR is the ferromagnetic austenite phase and that below TM or TR is the paramagnetic or weak ferromagnetic martensitic phase. At constant temperature, a magnetic field-induced strain was observed with a value of 1.0 × 10−3, which indicates that this alloy is sensitive to magnetic fields. Strong magneto-structural coupling was revealed by the magnetic properties and phase transitions.

  • Influence of Primary-Recrystallization Texture on Selective Growth of Goss Grains

    Takeshi Omura, Yasuyuki Hayakawa

    pp. 14-21

    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.M2012303

    Abstract

    A grain-oriented electrical steel has a significantly low iron loss by selective growth of grains with {110}< 001> orientation called as Goss orientation. The selective growth of Goss grains is generally attained by making use of a phenomenon termed ‘secondary recrystallization’. We have already investigated primary recrystallized grains encroached easily by Goss grain and discussed influence of primary-recrystallization texture on the selective growth of Goss grains roughly.
    This paper investigates normal growth behavior of primary recrystallized grains in the middle of secondary-recrystallization annealing and discusses influence of primary-recrystallization texture on the selective growth of Goss grains in detail. In this study, several grain-oriented electrical steel samples were prepared by controlling the heating pattern in secondary-recrystallization annealing. The primary-recrystallization texture and primary recrystallized grain size were measured in samples before secondary-recrystallization annealing and in the middle of secondary-recrystallization annealing.
    The results are as follows. (1) In secondary-recrystallization annealing, the normal grain growth of primary recrystallized grains having misorientation angle between 25–40 degree to Goss orientation was high. (2) It was considered that the normal grain growth in the middle of secondary-recrystallization annealing had a large influence on selective growth of Goss grain. (3) The change of primary-recrystallization texture in the middle of secondary between heating patterns was caused by the change of the normal grain growth.
    Next, we predicted crystal orientation after the secondary recrystallization by the analysis of primary-recrystallization texture in the middle of secondary-recrystallization annealing. In the prediction, the frequency and the mobility dependence of misorientation angle are taken into account.
    The expected result showed good agreement with the experimental result. This result was the same as the reported result before. Additionally, it was considered that the nucleation frequency of Goss grain in the primary-recrystallization texture had influence on this expectation.

    Recommended Articles: Effects of Anti-phase Boundary on the Iron Loss of Grain Oriented Silicon Steel [ View more ]

    x

    Readers Who Read This Article Also Read

    1. Effects of Anti-phase Boundary on the Iron Loss of Grain Oriented Silicon Steel ISIJ International Vol.51(2011), No.6
    2. Evolution of Goss Orientation during Rapid Heating for Primary Recrystallization in Grain-oriented Electrical Steel ISIJ International Vol.51(2011), No.6
    3. Grain Boundary Characteristics of Isolated Grains in Conventional Grain Oriented Silicon Steel ISIJ International Vol.47(2007), No.6

  • Effect of Hybrid Surface Treatment Composed of Plasma Nitriding and Fine Particle Bombarding on Fatigue Strength of Ti–6Al–4V Alloy

    Tatsuro Morita, Noriaki Uehigashi, Chuji Kagaya

    pp. 22-27

    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.M2012262

    Abstract

    This study investigated the effect of hybrid surface treatment on the fatigue strength of Ti–6Al–4V alloy. The hybrid surface treatment was composed of plasma nitriding and fine particle bombarding (FPB). Plasma nitriding generated a hardened layer with no marked growth of the microstructure of the substrate, and subsequent FPB eliminated a compound layer formed outermost through plasma nitriding. Tensile strength was maintained at the initial level, although ductility was somewhat reduced by fracture of the hardened layer. Plasma nitriding decreased the fatigue strength because the brittle compound layer fractured at relatively low stress amplitude and hastened the propagation of cracks. On the other hand, the effect of the hardened layer appeared through the elimination of the compound layer, so that hybrid surface treatment greatly improved the fatigue strength. Correspondingly, a crack initiation site was found beneath the hardened layer and suggested that the formed layer strongly suppressed crack initiation from the surface.

  • Effect of Repeated Tempering on Abrasive Wear Behavior of Hypoeutectic 16 mass% Cr Cast Iron with Molybdenum

    Sudsakorn Inthidech, Pisizchai Kosasu, Sumpao Yotee, Yasuhiro Matsubara

    pp. 28-35

    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.M2012185

    Abstract

    The effects of hardness, volume fraction of retained austenite (Vγ) and the number of tempering (tN) on abrasive wear resistance of hypoeutectic 16 mass% Cr cast irons without and with Mo was investigated. After annealing, the specimens were austenitized at 1323 K for 5.4 ks and cooled by fan air cooling. The hardened specimen was repeatedly tempered, at most three times at 748–798 K for 7.2 ks. The abrasive wear resistance of heat-treated specimens was evaluated using a Suga wear tester (two-body-type abrasive test). In the as-hardened state, the hardness did not change but the Vγ increased gradually with an increase in the Mo content. In the tempered state, the hardness curves showed a secondary hardening as the tN increased due to the precipitation of secondary carbides and transformation of destabilized austenite to martensite. The wear loss increased in proportion to the wear distance in all specimens. The wear rate (Rw) varied depending on the tN and Mo content. The Rw decreased when the hardness was increased. The Rw increased first and then decreased as the tN increased. The highest wear resistance was obtained in the 3% Mo cast iron with triple tempering.

  • Effects of Ga Concentration, Heat Treatment and Deformation Temperature on Pseudoelasticity of Fe–Ga Polycrystals

    Hiroyuki Y. Yasuda, Takenori Maruyama

    pp. 36-42

    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.M2012266

    Abstract

    The pseudoelastic behavior of Fe–Ga polycrystals was examined focusing on the effects of Ga concentration, heat treatment and deformation temperature. Fe–Ga polycrystals solutionized at 800°C exhibited pseudoelasticity at room temperature based on reversible motion of 1/4<111> superpartial dislocations dragging an antiphase boundary (APB) in the D03 superlattice structure. In particular, at and above 25 at%Ga, paired 1/4<111> superpartials dragging the next-nearest-neighbor APB were found to play an important role in the pseudoelasticity. The amount of strain recovery at room temperature was highest at 25 at%Ga. Moreover, heat treatment strongly influenced the pseudoelastic behavior of Fe–Ga alloys. For instance, the L12 and ω-like phases precipitating at higher Ga concentrations led to a decrease in strain recovery since the precipitates suppressed the reversible motion of 1/4<111> superpartials. On the other hand, pseudoelasticity based on twinning and untwinning of 2.2T-type pseudo-twins appeared at low temperatures, especially at −180°C. The energy of {211} pseudo-twins formed in the Fe–Ga alloys was so high that the twins tended to disappear during unloading resulting in the pseudoelasticity. However, the amount of strain recovery decreased if pseudoelasticities based on dislocation motion and twinning concurrently took place between −150 and −50°C.

  • Stability of Fatigued Dislocation Wall Structure in Coarse-Grained and Ultrafine-Grained Aluminum against Monotonic Tensile Deformation

    Yukito Nakanishi, Yoji Miyajima, Toshiyuki Fujii, Susumu Onaka, Masaharu Kato

    pp. 43-49

    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.M2012280

    Abstract

    Coarse-grained (CG) and ultrafine-grained (UFG) pure aluminum samples fabricated by equal channel angular pressing (ECAP) were cyclically deformed at 77 K under constant plastic strain amplitude. Monotonic tensile tests were performed at 300 and 77 K soon after the fatigue tests. In spite of the increase in the tensile strength of fatigued CG Al, tensile ductility decreased remarkably in comparison to that of as-annealed CG Al. On the other hand, the ultimate tensile strength (UTS) and tensile ductility of UFG Al were much higher at 77 K than those at 300 K. Furthermore, UFG Al at 77 K maintained high UTS and high tensile ductility even after fatigue tests. Microstructural observation has revealed that dislocation wall structure formed in fatigued CG Al persists after the monotonic tensile tests. However, dislocation wall structure formed in fatigued UFG Al disappeared during early stages of monotonic tensile tests at both 300 and 77 K. These results indicate that the dislocation wall structure in UFG Al is unstable against succeeding monotonic tensile deformation.

  • Tribology Property of Laser Cladding Crack Free Ni/WC Composite Coating

    Hu Cheng, Jian Yi, Zhigang Fang, Sheng Dai, Xianrui Zhao

    pp. 50-55

    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.M2012237

    Abstract

    In order to improve wear resistance, the Ni/WC composite coating was prepared on NAK80 mold steel surface by laser cladding technology. Phase and microstructure had been investigated by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Dry sliding tribological properties at room temperature of the coating had been researched by ball-on-disc wear tests. Results indicated that phase constituents of the coating were mainly composed of WC, W2C, Cr23C6, NiCr, CrB2 and γ-Ni, etc. There was a chemical metallurgical bonding between the coating and the steel substrate. Higher wear resistance of NAK80 mold steel was achieved after cladded by the Ni/WC composite coating, which was mainly related to dendrite phases Cr23C6 and hard phases WC, W2C dispersing in the coating.

  • Microstructures and Mechanical Properties of Austempering Cr–Mo (SCM 435) Alloy Steel

    Cheng-Yi Chen, Fei-Yi Hung, Truan-Sheng Lui, Li-Hui Chen

    pp. 56-60

    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.M2012317

    Abstract

    SCM435 is a Cr–Mo alloy steel and it is usually used to make the matrix of tempered-martensite by oil bath method, but it has some problems about reliability in the thin plate specimens. This research used the austempering heat treatment on the SCM435 thin plate specimen with a type of double loop and obtained the Cr–Mo bainite structure, and then we could further investigate the mechanical properties of SCM435 bainite materials. Experimental data showed that the stability of the mechanical properties of the specimen with austempering temperature 830°C for 25 min was better than that of 15 min. The size of the austenite grains affected the strength of thin plate bainite specimen. After austempering at 830°C for 25 min and salt bath at 290°C, the stability of the ultimate tensile strength (UTS) was better than that of the salt bath specimens at 310 and 330°C. The average hardness of all the specimens was more than HRA70. The specimen with austempering at 830°C for 25 min and salt bath at 290°C for 30 min had bigger grain size of the austenite and retained γ phase of 11.4 vol%. It also had higher hardness and strength. So, the austempering SCM435 alloy was improved for tensile strength comparing with traditional oil tempered-martensite process.

  • Solvent Extraction Separation of Mo and Co from Chloride Solution Containing Al

    Raju Banda, Seong Ho Sohn, Man Seung Lee

    pp. 61-65

    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.M2012287

    Abstract

    Solvent extraction studies were carried out to investigate the selectivity of some extractants towards Mo and Co from synthetic acidic chloride leach solution of spent HDS catalyst. The composition of the synthetic solution was (in ppm): Mo-394, Co-119, Al-1782 and 3 kmol/m3 of HCl. Among the several solvating and amine extractants that were tested, TOPO and Alamine 308 showed some potential towards the extraction of Mo and Co, respectively. The reasons for this greater extraction tendency of the corresponding extractants were also described thoroughly. Furthermore, the separation of Co and Al was investigated by varying the concentration of HCl. Finally, a possible extraction system for the separation of Mo and Co was presented. Our results can be utilized in developing a process for the recovery of Mo and Co from spent catalysts.

  • Protective Properties of SF6 under Various Carrier Gases for the Protection of Molten Mg

    Byeong Deok Lee, Ui Hyeon Beak, Ki Woo Lee, Gil Soo Han, Jeong Whan Han

    pp. 66-73

    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.M2012057

    Abstract

    Molten magnesium can oxidize rapidly in atmospheres containing oxygen. During the casting and handling of molten magnesium, it is essential to protect the melt from ignition. The protective gas normally contains air and/or CO2, and with a small amount of an inhibiting agent. This study examined the minimum amount of SF6 gas needed depending on the type of carrier gas, as well as the effects of the melt temperature, exposure time and SF6 concentration on the surface film of molten magnesium. The analysis methods of the surface film included the XPS/depth profile and SEM/EDS. The minimum amount of SF6 gas concentration determined over a wide a range of different carrier gases, such as air, N2 and CO2. The surface film thickness decreased with increasing SF6 concentration under all conditions, such as the melt temperature, exposure time and different carrier gas.

  • Recovery of Platinum from Chloride Leaching Solution of Spent Catalysts by Solvent Extraction

    Pan Pan Sun, Man Seung Lee

    pp. 74-80

    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.M2012320

    Abstract

    Platinum was recovered from the leaching liquor of spent petroleum catalyst by solvent extraction. Most of platinum in the spent catalysts was leached by using a mixture of HCl and H2O2 from the roasted spent catalyst. The effect of concentration of HCl/H2O2 in the solution, reaction temperature and pulp density was investigated. Complete extraction of Pt and Fe from the leaching liquor was obtained by Aliquat 336 at an O/A ratio of 1 in 2 stages. High purity solutions containing Fe and Pt were obtained from the loaded Aliquat 336 by scrubbing with dilute HCl solution and stripping with HClO4, respectively. Finally, HCl in the raffinate was regenerated by extraction with TEHA (Tri (2-ethylhexyl) amine) and then by stripping with water. The purity of HCl in the stripped solution was high enough to be reused in the leaching of spent catalysts. The optimum conditions in leaching, extraction and stripping together with the mass balance of the constituents of the spent catalysts in the whole process are reported.

  • Mesoscopic Modeling of Primary Recrystallization of AA1050 with Curvature-Driven Interface Migration Effect

    Dong-Kyu Kim, Ho Won Lee, Kyung-Hwan Jung, Yong-Taek Im

    pp. 81-89

    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.M2012267

    Abstract

    Primary recrystallization is an important phenomenon involved with cold deformation and heat treatment process. In the present investigation, a two dimensional probabilistic cellular automata model is used to simulate primary recrystallization of cold rolled AA1050, commercially pure aluminum. Electron backscatter diffraction measurement data was used as an input for the simulation to consider highly heterogeneous distribution of the stored energy and orientations compared to the randomly-distributed initial microstructure. Nucleation process was assumed to be site-saturated. Once a nucleus is formed, its recrystallization front will sweep the deformed regions by dissipating the stored deformation energy. In an attempt to contemplate anisotropic property of grain boundary migration, the grain boundary mobility was represented as a function of misorientation and the pressure was expressed as a function of dislocation density difference, curvature, and misorientation. The results of CA simulations were compared well with the JMAK theory in order to investigate the effects of nucleation criteria and curvature-driven pressure on the microstructure and the kinetics of primary recrystallization. This study revealed that local interface migration by curvature-driven pressure could significantly affect the recrystallization kinetics and microstructure morphology depending on the nucleation criteria.

  • Evaluation of Sensitivity of Remote Field Eddy Current Testing and Low-Frequency Eddy Current Testing for Inspecting Grooves of Metal Plate

    Jing Wang, Noritaka Yusa, Hongliang Pan, Toshiyuki Takagi, Hidetoshi Hashizume

    pp. 90-95

    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.M2012323

    Abstract

    We compare remote field eddy current testing and low-frequency eddy current testing from the viewpoint of sensitivity to back-side grooves in a metal plate. We carry out experiments using three metal plates with different depths of artificial grooves. A U-shape magnetic shield gives rise to a remote field eddy current as occurs in pipe inspection. The experiments show that the two methods have almost the same sensitivity to back-side grooves if a relatively low frequency and relatively far coil interval are used, which is also validated by three-dimensional finite-element simulations. We conduct numerical investigations to find the reason for this condition.

  • Dependence of Dose and He on Irradiation-Hardening of Fe-Ion Irradiated Fe–8Cr Model Alloy

    C. Liu, N. Hashimoto, S. Ohnuki, M. Ando, K. Shiba

    pp. 96-101

    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.M2012225

    Abstract

    An Fe–8Cr model alloy was irradiated in the TIARA facility with 10.5 MeV Fe3+ ions and/or 1.05 MeV He+ ions at 100–300°C to 0.1–10 dpa. Irradiated specimens were characterized using transmission electron microscopy and a nano-indentation technique. Visible defect clusters were not detectable by TEM for doses below ∼0.1 dpa, while spatially heterogeneous dislocation loop rafts were visible for a dose of 10 dpa in single ion irradiation. The loop rafts formation was impeded in dual ion irradiation with the implantation of helium atoms at 10 dpa. Ion irradiation led to increases in hardening with increasing doses. Further, log-log plots of irradiation hardening at 100, 250 and 300°C, which fit the dose dependence of the irradiation hardening using ΔH ∝ (dpa)n, indicate that the decreases of n values with lower temperatures are due to a tendency towards saturation in the irradiation hardening.

  • Global Substance Flow Analysis of Indium

    Akihiro Yoshimura, Ichiro Daigo, Yasunari Matsuno

    pp. 102-109

    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.M2012279

    Abstract

    Interest in recycling of rare metals has greatly increased recently because of the rapid growth in the demand for, and uneven distribution of, natural resources. Substance flow analysis (SFA) is a useful tool for determining the flow of substances in specific geographic regions. However, few SFAs have been conducted for rare metals. In this paper, we focus on indium and conduct SFAs of indium both in Japan and globally. Indium is primarily used as indium tin oxide (ITO), whose end uses can be categorized into two groups: liquid crystal displays and plasma panel displays; these are then assembled into final products. We quantified the flow of indium during its life cycle through mining, smelting and refining, manufacturing, use and waste management. For mining, smelting and refining, data were collected on the indium content in ore and production of primary metallic indium during 1999–2008. For manufacturing, we estimated the content of indium in final products, and estimated the input of indium in production as ITO in Japan. Then, we extrapolated the result to an SFA at the global scale. In-use stock and discarded indium were estimated by dynamic SFA, in which time-series data on the input of indium into final products and their lifetime distribution were used. We considered the loss of indium in each process to be the potential recyclable amount. We found that the extraction rate of indium in the mining, smelting and refining process was 8–11%, and the loss of indium in this process was 4,826 t in 2004. The loss in manufacturing amounted to 316 t, the in-use stock of indium was 116 t and the discarded indium in end-use products amounted to 5 t globally in 2004. Therefore, it was concluded that the biggest recovery potential of indium is during mining, smelting and refining.

  • Controlling 3D Percolation Threshold of Conductor-Insulator Composites by Changing the Granular Size of Insulators

    Kazuhito Shida, Ryoji Sahara, Hiroshi Mizuseki, Yoshiyuki Kawazoe

    pp. 110-113

    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.M2012227

    Abstract

    For a binary distribution of insulating particle sizes, we estimate the percolation threshold on a cubic lattice (3D). This work extends our previous investigation of a similar size distribution model in two dimensions (2D) where we found a drastic (∼13%) reduction in the percolation threshold (Shida et al. Materials Transactions Vol. 51, No. 6). For three-dimensional cases, the result is qualitatively similar to the corresponding two-dimensional cases: we found a significant decrease in the percolation threshold compared to the monodisperse cases.

  • Preparation of Niobium Powders for Solid Electrolyte Capacitors through Hunter Process Using Metallothermic Reduction Method

    Jae-sik Yoon, Jae-yeol Yang, Ji-myon Lee, Soon-jik Hong

    pp. 114-118

    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.M2012261

    Abstract

    The niobium capacitor shows somewhat more unstable characteristics than the commercial tantalum capacitors, but it will be nonetheless considered as an excellent substitute of tantalum capacitors in the future. In this study, niobium powder is fabricated by metallothermic reduction process using K2NbF7 as a raw material, KCl and KF as diluents, and Na as a reducing agent. The niobium particle size greatly decreases from 0.7 to 0.2 µm as the amount of diluent increases. However, when a higher surface area of niobium powder is desired, more amounts of diluents are used in the said method. The niobium powder morphology and particle sizes are very sensitive to the amount of sodium excess, thus the particle size of niobium powder increases with increases in the amount of sodium excess. When more diluent and sodium are used, the niobium powder is contaminated further by impurities such as Fe, Cr, Ni and others.

  • Sintering Properties of Ti–6Al–4V Alloys Prepared Using Ti/TiH2 Powders

    J.-M. Oh, K.-H. Heo, W.-B. Kim, G.-S. Choi, J.-W. Lim

    pp. 119-121

    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.M2012304

    Abstract

    Ti–6Al–4V alloy specimens were prepared by sintering Ti/TiH2 powders with pre-alloyed TiAl and Al–V powders. Changes in the sintered density, Vickers hardness, and phase structure of the Ti–6Al–4V (Ti6Al4V) and hydrogenated Ti–6Al–4V (H-Ti6Al4V) alloys as a function of the vacuum sintering temperature (700–1,300°C) were investigated. The sintered density and Vickers hardness of the Ti6Al4V and the H-Ti6Al4V alloys increased as the sintering temperature increased, while the concentration of oxygen considerably decreased with increasing sintering temperature. The oxygen concentration of the H-Ti6Al4V alloy was lower than that of the Ti6Al4V alloy. The sintered density and Vickers hardness values of the Ti6Al4V and H-Ti6Al4V alloys were almost the same. These results suggest that the preparation of Ti6Al4V alloy using TiH2 powder is more cost-effective and produces sintered products with lower oxygen concentrations.

  • Transmission Electron Microscopy in the Heat Affected Zone of an AISI 304 Austenitic Stainless Steel Welded with the Application of a Magnetic Field of Low Intensity

    Francisco F. Curiel, Rafael García, Victor H. López, Marco A. García, José Lemus

    pp. 122-125

    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.M2012260

    Abstract

    A transmission electron microscopy (TEM) study was carried out of the heat affected zone (HAZ) of an AISI 304 austenitic stainless steel gas metal arc welded with a magnetic field of 14.7 mT. Thin foils for TEM observation were prepared from the as-received 304 stainless steel and the HAZ of samples welded with and without magnetic field. M7C3 carbides were observed in conventional bright field (BF) and high resolution (HR) confirmed their presence in the as-received stainless steel. Elemental line scans performed in the base metal showed that the austenite/M7C3 interface was Cr-depleted in the austenite side. The results revealed that welding with magnetic field modified the distribution of Cr within the carbides and healed the Cr-depleted zones. This evidence accounts for the enhanced corrosion behaviour previously reported by the authors and strengthens the proposed mechanism where the interaction between the external magnetic field and the magnetic field generated by the direct current of the welding process promotes diffusion of Cr in short distances, healing thus Cr depletion.

  • Erratum

    pp. 126-126

    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.ERM201202

  • © 2013 The Japan Institute of Metals and Materials

Article Access Ranking

26 Jun. (Last 30 Days)

  1. Perspective toward Long-term Global Goal for Carbon Dioxide Mitigation in Steel Industry Tetsu-to-Hagané Vol.105(2019), No.6
  2. Hydrogen Embrittlement Susceptibility Evaluation of Tempered Martensitic Steels Showing Different Fracture Surface Morphologies ISIJ International Advance Publication
  3. Production and Technology of Iron and Steel in Japan during 2018 ISIJ International Vol.59(2019), No.6
  4. Effect of a Zn Interlayer on the Adhesion Strength and Corrosion Resistance of Zn–Mg Coated TRIP Steel ISIJ International Vol.59(2019), No.6
  5. A Kinetic Model of Mass Transfer and Chemical Reactions at a Steel/Slag Interface under Effect of Interfacial Tensions ISIJ International Vol.59(2019), No.5
  6. Fundamentals of Silico-Ferrite of Calcium and Aluminium (SFCA) Iron Ore Sinter Bonding Phase Formation: Effects of Titanium on Crystallisation during Cooling ISIJ International Vol.59(2019), No.6
  7. Evaluation of the Structure and Strength of Coke with HPC Binder under Various Preparation Conditions ISIJ International Advance Publication
  8. Recycling of Blast Furnace Sludge to the Blast Furnace via Cold-Bonded Briquettes: Evaluation of Feasibility and Influence on Operation ISIJ International Advance Publication
  9. Improvement of Sinter Strength and Reducibility through Promotion of Magnetite Ore Oxidation by Use of Separate Granulating Method ISIJ International Vol.59(2019), No.5
  10. Effects of Surface Microstructure on Selective Oxidation Morphology and Kinetics in N2 + 5%H2 Atmosphere with Variable Dew Point Temperature ISIJ International Vol.59(2019), No.5

Search Phrase Ranking

26 Jun. (Last 30 Days)

  1. blast furnace
  2. blast furnace permeability
  3. blast furnace productivity
  4. assimilation
  5. bubbling ladle
  6. inclusions
  7. isij xafs
  8. lme
  9. phosphatability
  10. phosphate treatment