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MATERIALS TRANSACTIONS Vol. 59 (2018), No. 10

ISIJ International
belloff
オンライン版ISSN: 1347-5320
冊子版ISSN: 1345-9678
発行機関: The Japan Institute of Metals and Materials

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キーワードランキング

03 Dec. (Last 30 Days)

MATERIALS TRANSACTIONS Vol. 59 (2018), No. 10

High-Strength Ti-Based Alloys Containing Fe as One of the Main Alloying Elements

Dmitri V. Louzguine-Luzgin

pp. 1537-1544

DOI:

10.2320/matertrans.M2018114

抄録

As well as the most of other 3d late transition metals Fe is a good β-Ti stabilizer, has a large solid solubility in β-Ti and owing to the atomic size difference with Ti can enable significant solution strengthening. The structure and mechanical properties of Ti alloys containing significant amount of Fe (or Fe together with Co, Cu and other elements) are reviewed in the present work. At high content of the late transition metals (for example, more than about 15 at% of Fe) the structure of these alloys consist of the rounded primary dendrites of an ordered cP2 intermetallic compound and an eutectic consisting of the cP2 intermetallic compound and a supersaturated cI2 β-Ti solid solution. cP2+cI2 phase Ti–Fe alloys, their derivatives: Ti–Fe–Co, Ti–Fe–Cu, etc…, and cI2 β-Ti solid solution alloys containing Sn and Nb exhibit high compressive strength and plasticity. At lower Fe content a supersaturated β-Ti solid solution single phase structure is formed. However, these alloys also show good mechanical properties especially when alloyed with Sn and Nb. The structure and properties of various kinds of such alloys are discussed in the present paper.

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On the Optimal Glass-Forming Composition of Al–Co–Y Amorphous Alloys

Xianzhong Xiong, Jiaojiao Yi, Lingti Kong, Michael Ferry, Jinfu Li, Yaohe Zhou

pp. 1545-1550

DOI:

10.2320/matertrans.M2018177

抄録

Al–Co–Y alloys were suction cast under identical conditions into a wedge-shaped copper mold for investigating the compositional dependence of glass-forming ability (GFA). The optimal glass-forming composition was determined to be Al89Co5.5Y5.5, whose Al content is evidently larger than the findings of the optimal glass formers in other Al–TM–Y alloy systems. A reason is that Co-centered clusters tend to share vertexes and edges rather than faces with the surrounding clusters in Al–Co–Y amorphous alloy, and more Al atoms are required. When Al89Co5.5Y5.5 amorphous alloy and its neighbors were isochronally annealed in a differential scanning calorimeter, no glass transition could be observed and the primary crystallization phase was invariably fcc-Al.

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Effect of Dissolved Impurities on the Rate of Recovery and Recrystallization in an A1050 Aluminum Hot-Rolled Sheet

Hideo Yoshida, Yuko Tamada, Mineo Asano, Yoshimasa Ookubo

pp. 1551-1559

DOI:

10.2320/matertrans.L-M2018834

抄録

The effect of the soaking conditions of ingots on the rate of recovery and recrystallization in an A1050 hot-rolled sheet during annealing at 350°C was investigated. The rate of the recovery and recrystallization with no soaking and 600°C/8 h WQ (water quenching) was slower than that of 450°C/8 h FC (furnace cooling). Many dissolved impurities (Fe, Si), which were contained in the no soaking and 600°C/8 h WQ conditions cause the delay in the recovery and recrystallization. Particularly, in the no soaking condition, no precipitation was observed within the grains of the ingot and the hot-rolled sheet. On the other hand, in the 450°C/8 h FC condition, the recovery and recrystallization was too fast. Fine granular precipitates of less than 0.1 µm in diameter were observed and there were few dissolved impurities in the ingot and the hot-rolled sheet. Pinning of the subgrain boundaries by these fine precipitates was not observed. The normalized change in the Vickers hardness and electrical conductivity was divided into a recovery reaction and a recrystallization one, respectively, by a newly developed rate equation. The role of the impurities in the recovery and recrystallization was explained and clarified by the result of using this equation. This Paper was Originally Published in Japanese in J. JILM 67 (2017) 284–291.

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Martensitic Transformation Induced in Ti–15V–7Al Alloy at Low and High Temperatures

Yoshito Takemoto, Miyu Tsunekawa, Yuji Manabe, Soushi Itano, Yuji Muraoka

pp. 1560-1566

DOI:

10.2320/matertrans.M2018185

抄録

Ti–15V–7Al alloy, which has a composition exhibiting peculiar phenomena upon tempering, was prepared and its martensitic transformation behavior during cooling and heating was investigated. The structure of the quenched specimen mostly consisted of the β-phase and a small quantity of α′′ martensite near the grain boundaries. When heating an elastically bent strip of the specimen, spontaneous bending occurred, as reported for some other alloys. Subzero treatment using LN2 newly induced some martensites around the prior martensites formed by quenching, but no martensites were formed in the single β region. The formation of the martensites by the subzero treatment exhibited time dependence. Even tempering at 550°C for 3 s, induced the formation of coarse martensites throughout the specimen. All martensites formed by the quenching, the subzero treatment or the tempering disappeared completely upon heat treatment at 200°C for 300 s, resulting in a single β-phase. However, the coarse martensites were regenerated from the single β-phase by tempering at 550°C for a short time, which means that the martensite behavior in the range of 200–550°C is reversible. Continuous isothermal aging at 550°C led to marked hardening through the process β → coarse α′′ → fine α′′ → β + fine α. Both an MS curve and a free-energy model, which can explain the martensite formation at low and high temperatures and the annihilation at 200°C, are proposed. This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 82 (2018) 307–313.

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Characterization of Antiphase Boundary-Like Structure of B33 Martensite in Zr–Co–Pd Alloy

Mitsuhiro Matsuda, Yoshimasa Shinagawa, Kazuki Takashima, Masatoshi Mitsuhara, Minoru Nishida

pp. 1567-1573

DOI:

10.2320/matertrans.M2018146

抄録

The antiphase boundary (APB)-like structure of B33 martensite in a Zr–Co–Pd alloy was investigated by means of conventional transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy. The APB-like structure had atomic shifts along both the c-axis on the (010)B33 basal plane and the b-axis on the (001)B33 plane. The displacement vector of the APB-like structure could be expressed as R = 〈0, 1/4, 1/2〉B33. The formation mechanism of the APB-like structure was also elucidated.

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Characterization of CrN-Based Hard Coating Materials with Addition of GaN

Yusei Mizuno, Tadachika Nakayama, Hisayuki Suematsu, Tsuneo Suzuki

pp. 1574-1577

DOI:

10.2320/matertrans.MAW201806

抄録

Cr1−xGaxN thin films with various GaN concentrations were prepared on Si(100) substrates by pulsed laser deposition in order to clarify the effects of the GaN content on the material characteristics. The compositions of these films were determined by Rutherford backscattering spectroscopy, while crystal structures were elucidated using Fourier transform infrared spectroscopy and X-ray diffraction, and hardness values were measured by nanoindentation. Analyses determined that x was in the range of 0 to 0.51 and, at x ≤ 0.31, a single B1-(Cr,Ga)N phase was present. In those films for which x ≥ 0.38, a secondary phase based on B4-GaN also appeared. The hardness increased with increases in x up to 0.31 as the thin films maintained a single B1-(Cr,Ga)N phase, and a maximum hardness of 29.4 GPa was obtained at x = 0.31.

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Prediction of Shrinkage Cavity in Heavy-Section Ductile Cast Iron Using CAE Considering Volume Change during Solidification

Yutaka Miyamoto, Haruki Itofuji

pp. 1578-1584

DOI:

10.2320/matertrans.F-M2018833

抄録

A new analysis parameter, which is the volume balance during solidification in heavy section ductile cast irons, was adopted to predict shrinkage cavities by computer simulation. To realize higher precision and quantify the behavior of expansion/contraction during solidification, the temperature and solidification ratio of each reaction stage from the start to completion of solidification were determined by the tangent line method. The expansion/contraction amounts of each reaction were calculated from chemical compositions of carbon and silicon and the initial temperature of the test material. Finally, the expansion/contraction degree was calculated by dividing the amounts of the expansion/contraction at each reaction by the solidification ratio. The quantified value was input into the casting simulation software as the expansion/contraction amounts. The result showed better matching compared to the actual shrinkage phenomenon. This Paper was Originally Published in Japanese in J. JFS 90 (2018) 175–181.

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Cladding of Al Layer onto Mild Steel Substrate Using Al Powder and Its Structure and Properties

Fumitaka Otsubo, Hidenori Era

pp. 1585-1590

DOI:

10.2320/matertrans.P-M2018835

抄録

Pure aluminum powder with grain sizes of 45 to 10 µm preformed on aluminum (A1050) and mild steel (SPCC) substrates were rolled to form cladding materials at room temperature in air. The partial rolling reduction of the Al cladding layer was smaller than that of the A1050 substrate in an Al powder/A1050 cladding sheet. In contrast, the partial rolling reduction of the Al cladding layer was larger than that of the SPCC substrate in an Al powder/SPCC cladding sheet. The difference in the partial rolling reduction of the cladding layers and SPCC substrates became smaller with increasing total rolling reduction of the Al powder/SPCC cladding sheets. The shear adhesion strength of the Al powder/SPCC cladding sheet was about 40 MPa, which decreased to about 10 MPa after heat treatment at 773 K for 3.6 ks. The intermetallic compounds were formed between the cladding layer and the substrate after heat treatment at 773 K for 3.6 ks. Also, the cladding layer showed excellent oxidation resistance compared with cast iron after heat treatment at 1073 K for 36 ks in air, though light oxidation occurred in specimens after heat treatment at 773 K for 36 ks in air. This Paper was Originally Published in Japanese in J. JSTP 58 (2017) 582–586.

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Comparison of Microstructure and Tribological Properties of Plasma, High Velocity Oxy-Fuel and Detonation Sprayed Coatings from an Iron-Based Powder

Lu Xie, Yue-Ming Wang, Xiang Xiong, Zhao-Ke Chen

pp. 1591-1595

DOI:

10.2320/matertrans.M2018141

抄録

The microstructure and tribological properties of Fe-based amorphous coatings fabricated by plasma spray, high-velocity oxygen-fuel (HVOF) spray and detonation spray have been compared. The relationship between spray technique, amorphous content, porosity and wear resistance behavior was investigated. The microstructures of the coatings were mainly composed of amorphous phase. The amorphous content of the coatings made by various spray techniques were 79.39%, 85.26% and 88.14%, respectively. The coatings exhibited better wear resistance than the stainless steel substrate. The detonation sprayed coating obtained the best wear properties, and the wear mechanism was typical fatigue wear.

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Microstructural Characteristics and Properties of Adding Vanadium Carbide Powders to Vanadis 4 Tool Steel through Vacuum Sintering and Heat Treatments

Kuo-Tsung Huang, Shih-Hsien Chang, Kuang-Yao Lee, Ming-Wei Wu

pp. 1596-1602

DOI:

10.2320/matertrans.M2018186

抄録

In this study, different amounts of vanadium carbide (VC) powders (1, 3 and 5 mass%) are mixed and added to Vanadis 4 steel powders. The composite powders are sintered at 1225, 1250, and 1275°C for 1 h, respectively. The experimental results show that the optimal sintering temperature for Vanadis 4-VC composites is 1250°C. The Vanadis 4 specimens with a 3% VC addition possess the highest transverse rupture strength (TRS) value of 1953.3 MPa, as well as the highest polarization resistance (1.84 × 104 Ω·cm2), while with a 1% VC addition obtain the highest hardness value of 82.9 HRA after sintering at 1250°C. Furthermore, a microstructural evaluation reveals that the round-shaped M23C6 carbides uniformly located on the grain boundaries are gradually increased as VC particles are added, and the fine particle-shaped (V, Fe) carbides are uniformly dispersed in the matrix. After heat treatment, the VC carbides decompose and re-precipitate refined M23C6 and (Cr, Fe) carbides around the grain boundaries and within the grains, which results in dispersion strengthening and precipitation hardening. The results clearly show that heat treatment effectively improves the microstructure and strengthens the matrix of the Vanadis 4-VC composites.

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Imposition Time Dependent Microstructure Formation in 7150 Aluminum Alloy Solidified by an Electromagnetic Stirring Technique

Mingjun Li, Yuichiro Murakami, Isao Matsui, Naoki Omura, Shuji Tada

pp. 1603-1609

DOI:

10.2320/matertrans.M2017357

抄録

In the present study, a three-phase induction coil was used to generate a rotating magnetic field (RMF) when three-phase alternating current flowed through the coil. We solidified the 7150 aluminum alloy (main composition: Al–6.1 mass%Zn–2.2 mass%Mg) in the RMF where electromagnetic torque could be exerted upon the alloy and thus electromagnetic stirring (EMS) could be generated upon the crystallizing melt. The imposition pattern and time for EMS processing were tailored, making it possible for the liquid column to be rotated along clockwise (CW) and counterclockwise (CCW) alternatively. We solidified the alloy when periodic CW/CCW rotation was imposed and then examined the microstructure as function of reverse imposition time, exhibiting a strong dependence on imposition time. The microstructure formation was discussed when considering the substantial difference in electrical resistivity between the primary solid solution and remaining liquid, which led to uncoupled movement between the primary mobile solid and remaining sluggish liquid. The movement of the solid was further diagnosed when considering the fluid resistance that lagged the movement and thus lowered the velocity difference between the mobile solid and the sluggish liquid when the imposition time was extended. The lowered velocity difference could generate reduced interaction between the solid and liquid and thus in some areas, coarse dendritic embryos could be observed. This effect was further verified when continuous one-way rotation was applied, which resulted in the formation of developed dendrites in the alloy.

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Densification and Grain Growth of Large-Sized Polycrystalline Al2O3 during a Two-Step Pulsed Electric Current Sintering Process

Hien H. Nguyen, Makoto Nanko

pp. 1610-1615

DOI:

10.2320/matertrans.M2018055

抄録

In this study, transparent polycrystalline Al2O3 with a diameter of 30 mm was fabricated by two-step pulsed electric current sintering (TS-PECS) at two different heating rates, 100 and 10°C/min. The overall TS-PECS process was divided into parts and was stopped at various positions along the timeline. The relative density and grain size of the Al2O3 samples obtained from each stop were evaluated. In general, the results show that the heating rate changed the densification rate in each sintering stage but did not strongly affect the final density. However, it dramatically influenced the grain growth of Al2O3. With the higher heating rate, the dynamic grain growth was assumed to enhance the grain growth rate because of the high concentration of defects, especially in the last stage of sintering. Especially, a grain size refinement phenomena was observed during the sintering process of polycrystalline Al2O3 for the first time.

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Influence of Processing Conditions for Nickel Particles Prepared by Pulsed Microwave Heating in Liquid

Keisuke Yasuda, Naoto Koshizaki, Yoshie Ishikawa

pp. 1616-1620

DOI:

10.2320/matertrans.MAW201807

抄録

A technique, pulsed microwave heating in liquid, is examined under the condition for time- and space-selective heating of nickel particles dispersed in liquid. This technique is modified from the pulsed laser melting in liquid for submicrometer spherical particle fabrication. When nickel particles that are 50 µm in size or larger were dispersed in low-dielectric-loss hexane with a concentration of 2 g L−1 or higher, particle became large with smooth surface by microwave irradiation, suggesting that the particle surface temperature was elevated over the melting point. Pulsed microwave irradiation with short pulse width and large pulse frequency is effective for the fabrication of particles with smooth surfaces. Thus, pulsed microwave melting in liquid would provide a new processing technique at high temperatures in a liquid environment.

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Thermoelectric Generation System Using the Exhaust Heat of Generators

Hideo Wada, Masahiro Haga

pp. 1621-1627

DOI:

10.2320/matertrans.E-M2018836

抄録

We demonstrated the thermoelectric power generation system utilizing exhaust heat from generators. In this system, gas flow is disturbed, so the alternately arranged pin fins with high thermal conductivity were adopted as heat exchangers. Furthermore, the exhaust heat power generation data was measured and compared with the simulation model of the fuel cell system. As a result, in the 700 W class fuel cell, the measured data agreed well with the simulation model results, and it was found that 2.8 W power generation energy was obtained. Also, in the 10 kW class generator with four thermoelectric power generation units in tandem, 268.4 W power generation energy was estimated. This Paper was Originally Published in Japanese in J. Thermoelec. Soc. Japan 14 (2018) 126–131.

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Features of Crack Size Distribution- and Voltage Probe Spacing-Dependences of Critical Current and n-Value in Cracked Superconducting Tape, Depicted by Simulation

Shojiro Ochiai, Hiroshi Okuda, Noriyuki Fujii

pp. 1628-1636

DOI:

10.2320/matertrans.MAW201805

抄録

Features of the dependence of critical current and n-value on the width of crack size distribution and voltage probe spacing in cracked superconducting tape were investigated by simulation and analysis of the simulation results. From the simulation results, the following features were confirmed. The variation of critical current and n-value with position along the longitudinal direction of the superconducting tape increases with increasing width of crack size distribution for any voltage probe spacing, and it decreases with increasing voltage probe spacing for any width of crack size distribution. The n-value varies more sensitively to the width of crack size distribution and voltage probe spacing than critical current. Then, from the analysis of the simulation results, it was confirmed that the largest crack among all cracks plays a major role in determination of critical current, and the phenomenon “critical current decreases with increasing width of crack size distribution and voltage probe spacing” is attributed to the increase in size of the largest crack. Also, it was shown that the upper and lower bounds of critical current and n-value of the region, which is in between the voltage probes and consists of local sections/local regions, can be calculated by using the voltage-current curve of the local section/local region with the largest crack. The application of this calculation method to the simulation results revealed that, in any voltage probe spacing, critical current value shifts from the lower to upper bound, and, in contrast, n-value shifts from the upper to lower bound with increasing width of crack size distribution. Also it was revealed that the difference between the upper and lower bounds becomes smaller and both bounds’ values become closer to the actual critical current and n-values, when the voltage-current curve of longer local region is used in calculation.

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Effective Decrease of the Thermal Conductivity Caused by Hf in Fe(V0.955−xHf0.045Tix)Sb Half-Heusler Phase

Kévin Delime-Codrin, Ghodke Swapnil, Dogyun Byeon, Robert Sobota, Masaharu Matsunami, Tsunehiro Takeuchi

pp. 1637-1644

DOI:

10.2320/matertrans.M2018171

抄録

The thermoelectric properties of the Fe(V0.955−xHf0.045Tix)Sb half-Heusler (HH) phase were studied in the temperature range from 300 to 800 K. We employed Hf- and Ti-substitutions for V in the FeVSb-based HH phase for reducing the lattice thermal conductivity and tuning the carrier concentration, respectively. The samples prepared with the composition of Fe(V0.955−xHf0.045Tix)Sb (0.000 ≤ x ≤ 0.075) consisted almost solely of the half-Heusler phase. We succeeded in significantly decreasing the lattice thermal conductivity κlat ≈ 2.1 W m−1K−1 for Fe(V0.88Hf0.045Ti0.075)Sb while keeping appropriate carrier concentration for the optimized transport properties. However, the highest ZT value was not significantly increased but kept rather low at 0.55, mainly due to the reduction in the Seebeck coefficient. The mechanism leading to the reduction in Seebeck coefficient was revealed by the means of first principles band calculations.

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Magnetic and Structural Properties of MnCoGe with Minimal Fe and Sn Substitution

Masahira Onoue, Ryota Kobayashi, Yoshifuru Mitsui, Masahiko Hiroi, Kohki Takahashi, Akihiro Kondo, Koichi Kindo, Yoshiya Uwatoko, Keiichi Koyama

pp. 1645-1650

DOI:

10.2320/matertrans.M2018183

抄録

The magnetic and structural properties of MnCo0.92Fe0.08Ge1−xSnx (x = 0.02, 0.05, and 0.1) were investigated. A first-order magnetic transition was observed, which was accompanied by the martensitic transformation from a hexagonal Ni2In-type to an orthorhombic TiNiSi-type structure in the vicinity of 320 K for x = 0.02 and 170 K for x = 0.05 with thermal hysteresis of approximately 20 K. The magnetization of MnCo0.92Fe0.08Ge0.95Sn0.05 was estimated to be 102 Am2 kg−1 in 5 T at 10 K. High field magnetization curves up to 55 T for MnCo0.92Fe0.08Ge0.95Sn0.05 indicated the field-induced martensitic transformation. Mössbauer spectroscopy experiments revealed that Fe atoms occupied 79%–85% in the Co-site and 21%–15% in the Mn-site.

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Precipitation of Oxide Particles in Oxide Dispersion Strengthened (ODS) Ferritic Steels

Naoko Oono, Shigeharu Ukai

pp. 1651-1658

DOI:

10.2320/matertrans.M2018110

抄録

This study tries to reveal the mechanism of forming fine and dense oxide particles in oxide dispersion strengthened (ODS) ferritic steel during heat treatment after mechanical alloying (MA). The MAed powders with and without titanium are set to the heat treatment from 873 K to 1423 K and analyzed by small angle X-ray scattering and X-ray diffraction using synchrotron radiation, transmission electron microscopy, and 3D atom probe. Yttrium and oxygen are segregated along the grain-boundaries induced by MA and form clusters after 873 K annealing. Fine oxide particles are densely formed before primary-recrystallization of the nano-sized grains induced during MA, at 973 K. The formation of cubic-Y2O3 and Y2Ti2O7 are observed at 1273 K and above, where the size reduction of the oxide particles by Ti-addition is clearly shown.

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Transfer Behavior of Fe Element in Nickel Slag during Molten Oxidation and Magnetic Separation Processes

Yingying Shen, Ziniu Huang, Yanyun Zhang, Junkai Zhong, Wenjuan Zhang, Yan Yang, Min Chen, Xueyan Du

pp. 1659-1664

DOI:

10.2320/matertrans.M2018002

抄録

High-percentage iron resources in nickel slags were recovered as magnetite via molten oxidation process, and the transfer behavior of Fe element was studied. The elemental distribution in oxidized slag samples, the influence of atmosphere, holding temperature and time on magnetite crystal growth, and Fe element distribution in magnetic materials were also investigated. It was found that magnetite could be produced from fayalite or hortonolite in nickel slags during molten oxidation with CaO as a modifier, air as an oxidizer, accompanying with the enrichment of Fe, Co, Ni and Cu. The select of atmosphere is very important during the precipitation and growth of the magnetite crystals. The magnetite crystals precipitated invisibly or slightly in argon atmosphere, while exhibited dendritic structures with crystallization content of ∼18.5% in air atmosphere. Especially, after blowing air into molten slag for 30 min, magnetite crystals develop well-distributed and complete, resulting in its crystallization content increases up to 33.5%. The Fe content in the matrix of oxidized samples remained approximately constant after holding for 20 min. Mössbauer spectra analysis indicates that the 89.6% of Fe exists in magnetite phases, while only 10.4% of Fe in hedenbergite. It was also found that Ni and Co simultaneously concentrate in the magnetite phase, indicating that Fe, Ni, and Co can be recovered effectively from nickel slag.

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Removal of Heavy Metals from Tailing in Citrate Solution with Ferric Chloride

Tam Thi Nguyen, Kyoungkeun Yoo, Manis Kumar Jha, Jayhyun Park, Uikyu Choi, Hongil Choe, Jae-chun Lee

pp. 1665-1668

DOI:

10.2320/matertrans.M2018152

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Leaching tests were performed in citrate solution with Fe3+ to investigate the leaching behaviors of As, Zn, Pb, and Cu from tailings, which has been known as soil contaminant sources near abandoned mines. The combination of citrate and Fe3+ was selected based on the previous study, which reported that the oxidants such as Fe3+ was required to remove heavy metals from stable forms like sulfides because citrate could leach metals only in carbonate and oxide forms. The leaching efficiencies of heavy metals except As increased with increasing agitation speed, initial Fe3+ concentration, temperature, but decreasing pulp density; e.g. the efficiencies of Zn, Pb, Cu were almost 100% in the 1 M citric solution with 3 M Fe3+ at 400 rpm and 50°C with 0.25% pulp density within 3 hr, but 7.4% for As. The initial oxidation-reduction potential (vs Ag/AgCl) was reduced from 713.5 mV in FeCl3 solution to 656.1 mV in citrate solution with FeCl3, which would inhibit the dissolution of As because As mineral such as arsenopyrite has high open circuit potential. These results indicate that As could be selectively left in the leach residue using citrate solution with Fe3+.

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