Journal of Powder Materials

Volume 19(4); August 2012

Effect of Cu and DyF₃ Powder Additions on the Coercivity of Sintered Nd-Fe-B Magnets: S. NamKung, M.W. Lee, D.R. Dhakal, T.H. Lim, T.H. Kim, S.R. Lee, T.S. Jang; J Korean Powder Metall Inst. 2012;19(4):247-252.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.247

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Abstract PDF: Effect of Cu and DyF_3 powder mixing with Cu-free (Nd, Dy)-Fe-B jet-milled powder on the magnetic properties of sintered magnets was investigated. The coercivity of a magnet prepared from the Cu-free (Nd, Dy)-Fe-B powder was about 10 kOe even though the alloy powder already contained some Dy (3.5 wt%). When small copper powder was blended, however, the coercivity of the magnet increased almost 100%, exhibiting about 20 kOe. On the contrary, the coercivity enhancement was moderate, about 4 kOe, when dysprosium content in the sintered magnet was simply increased to 4.9 wt% by the addition of small DyF_33 powder.

Thermo-Mechanical Properties of Al₂TiO₅ Ceramics Stabilized with MgO and ZrO₂ Additives: Da-Mi Kim, Hyung-Tae Kim, Hyeong-Jun Kim, Ik-Jin Kim, Seong-Cheol Choi, Yong-Chan Kim, Jung NamKung, Sung-Soo Ryu; J Korean Powder Metall Inst. 2012;19(4):253-258.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.253

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The characteristics of Al_2TiO_5 ceramics were influenced by the additives and the heat treatment that controls the microcrack behavior at grain boundaries. The effect of additives on Al_2TiO_5 ceramics were investigated in terms of mechanical properties and thermal expansion at high temperature. The Al_2TiO_5 were synthesized at 1500°C, 1550°C and 1600°C for 2h by reaction sintering. The formation of Al_2TiO_5 phase was increased by additives that enhanced the volume of the microcrack that can lead to low thermal expansion. The mechanical properties of the stabilized Al_2TiO_5 ceramics were increased remarkably at 1100°C, 1200°C and 1300°C due to the oneset of mechanical healing of grain-bondary microcracks at a high temperature. The amount of microcrack was decreased at lower sintering temperature that causes the increase of mechanical properties at high temperature.

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The influence of different additives on microstructure and mechanical properties of aluminum titanate ceramics
Weiwei Chen, Anze Shui, Qingliang Shan, Jiawei Lian, Cong Wang, Jianqiao Li
Ceramics International.2021; 47(1): 1169. CrossRef

Effect of Powder Characteristic and Freeze Condition on the Pore Characteristics of Porous W: Na-Yeon Kwon, Sung-Tag Oh; J Korean Powder Metall Inst. 2012;19(4):259-263.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.259

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Dependence of the freeze-drying process condition on microstructure of porous W and pore formation mechanism were studied. Camphene slurries with WO_3 contents of 10 vol% were prepared by milling at 50°C with a small amount of dispersant. Freezing of a slurry was done in Teflon cylinder attached to a copper bottom plate cooled at -25°C. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at 800°C for 30 min, and sintered in the furnace at 900°C for 1 h. After heat treatment in hydrogen atmosphere, WO_3 powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about 70µm which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores with dendritic structure due to the growth of camphene dendrite depending on the degree of nucleation and powder rearrangement in the slurry.

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Fabrication of Porous W-Ti by Freeze-Drying and Hydrogen Reduction of WO3-TiH2 Powder Mixtures
Hyunji Kang, Sung Hyun Park, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2017; 24(6): 472. CrossRef
Synthesis of Aligned Porous Sn by Freeze-Drying of Tin Chloride/camphene Slurry
수룡 방, 승탁 오
Korean Journal of Materials Research.2015; 25(1): 27~31. CrossRef
Effect of Sublimable Vehicle Compositions in the Camphor-NaphthaleneSystem on the Pore Structure of Porous Cu-Ni
Na-Yeon Kwon, Myung-Jin Suk, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2015; 22(5): 362. CrossRef
Porous Mo–30wt.% W alloys synthesized from camphene/MoO3–WO3 slurry by freeze drying and sintering process
Ki Cheol Jeon, Beom Seok Kim, Young Do Kim, Myung-Jin Suk, Sung-Tag Oh
International Journal of Refractory Metals and Hard Materials.2015; 53: 32. CrossRef
Fabrication of Porous Cu-Ni by Freeze Drying and Hydrogen Reduction of CuO-NiO Powder Mixture
Han Gil Seo, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2014; 21(1): 34. CrossRef
Synthesis of porous Cu–Sn using freeze-drying process of CuO–SnO2/camphene slurries
Sung-Tag Oh, Wonsuk Lee, Si Young Chang, Myung-Jin Suk
Research on Chemical Intermediates.2014; 40(7): 2495. CrossRef
Fabrication of Porous Cu by Freeze-drying Process of Camphene Slurry with CuO-coated Cu Powders
Su-Ryong Bang, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2014; 21(3): 191. CrossRef
Effect of Solidification Condition of Sublimable Vehicles on the Pore Characteristics in Freeze Drying Process
Myung-Jin Suk, Ji Soon Kim, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2014; 21(5): 366. CrossRef
Freeze Drying for Porous Mo with Sublimable Vehicles of Eutectic System
Gyu-Tae Lee, Han Gil Seo, Myung-Jin Suk, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2013; 20(4): 253. CrossRef
Synthesis of Porous Cu-Sn by Freeze Drying and Hydrogen Reduction Treatment of Metal Oxide Composite Powders
Min-Sung Kim, Ho-Suk Yoo, Sung-Tag Oh, Chang-Yong Hyun
Korean Journal of Materials Research.2013; 23(12): 722. CrossRef
Fabrication of Porous Mo by Freeze-Drying and Hydrogen Reduction of MoO3/Camphene Slurry
Wonsuk Lee, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2012; 19(6): 446. CrossRef

Sintering and Rolling Behavior of Cu-50In-13Ga Ternary Alloy Powder for Sputtering Target: Dae-Won Kim, Yong-Ho Kim, Jung-Han Kim, Dae-Guen Kim, Jong-Hyeon Lee, Kwang-Bo Choi, Hyeon-Taek Son; J Korean Powder Metall Inst. 2012;19(4):264-270.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.264

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In this study, we mainly focus on the study of densification of gas-atomized Cu-50 wt.%In-13 wt.%Ga alloy powder without occurrence of crack during the forming process. Cu-50 wt.%In-13 wt.%Ga alloy powder was consolidated by sintering and rolling processes in order to obtain high density. The phase and microstructure of formed materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OM), respectively. Warm rolling using copper can result in the improvement of density. The specimen obtained with 80% of rolling reduction ratio at 140°C using cooper can have the highest density of 8.039g/cm3.

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Synthesis and Properties of a Ge2Sb2Te5Sputtering for Use as a Target by Spark Plasma Sintering
C.W. Bang, K.B. Kim, J.K. Lee
Journal of Korean Powder Metallurgy Institute.2014; 21(2): 137. CrossRef

Synthesis of SnO₂ Nanotubes Via Electrospinning Process and Their Application to Lithium Ion Battery Anodes: Young-In Lee, Yong-Ho Choa; J Korean Powder Metall Inst. 2012;19(4):271-277.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.271

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SnO_2 nanotubes were successfully synthesized using an electrospinning technique followed by calcination in air. The nanotubes were the single phase nature of SnO_2 and consisted of approximately 14 nm nanocrystals. SEM and TEM characterizations demonstrated that uniform hollow fibers with an average outer diameter of around 124 nm and wall thickness of around 25 nm were successfully obtained. As anode materials for lithium ion batteries, the SnO_2 nanotubes exhibited excellent cyclability and reversible capacity of 580mAhg-1 up to 25 cycles at 100mAg-1 as compared to SnO_2 nanoparticles with a capacity of sim200mAhg-1. Such excellent performance of the SnO_2 nanotube was related to the one-dimensional hollow structure which acted as a buffer zone during the volume contraction and expansion of Sn.

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Fabrication of Nanowire by Electrospinning Process Using Nickel Oxide Particle Recovered from MLCC
Haein Shin, Jongwon Bae, Minsu Kang, Kun-Jae Lee
journal of Korean Powder Metallurgy Institute.2023; 30(6): 502. CrossRef
A study on the synthesis of tin oxide crystalline by the liquid reduction precipitation method and hydrothermal process
Il-Jeong Park, Geon-Hong Kim, Dae-Weon Kim, Hee-Lack Choi, Hang-Chul Jung
Journal of the Korean Crystal Growth and Crystal Technology.2016; 26(3): 95. CrossRef
Improvement of Triboelectric Efficiency using SnO2 Friction Layer for Triboelectric Generator
No Ho Lee, Jae Rok Shin, Ji Een Yoo, Dong Hun You, Bon-Ryul Koo, Sung Woo Lee, Hyo-Jin Ahn, Byung Joon Choi
Journal of Korean Powder Metallurgy Institute.2015; 22(5): 321. CrossRef

Effect of Process Conditions on the Microstructure of Particle-Stabilized Al₂O₃ Foam: Rizwan Ahmad, Jang-Hoon Ha, Yoo-Dong Hahn, In-Hyuck Song; J Korean Powder Metall Inst. 2012;19(4):278-284.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.278

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Al_2O_3 foam is an important engineering material because of its exceptional high-temperature stability, low thermal conductivity, good wear resistance, and stability in hostile chemical environment. In this work, Al_2O_3 foams were designed to control the microstructure, porosity, and cell size by varying different parameters such as the amount of amphiphile, solid loading, and stirring speed. Particle stabilized direct foaming technique was used and the Al_2O_3 particles were partially hydrophobized upon the adsorption of valeric acid on particles surface. The foam stability was drastically improved when these particles were irreversibly adsorbed at the air/water interface. However, there is still considerable ambiguity with regard to the effect of process parameters on the microstructure of particle-stabilized foam. In this study, the Al_2O_3 foam with open and closed-cell structure, cell size ranging from 20µm to 300µm having single strut wall and porosity from 75% to 93% were successfully fabricated by sintering at 1600°C for 2 h in air.

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A Fatigue Fracture Study on TDCB Aluminum Foam Specimen of Type Mode III Bonded with Adhesive
J.H. Lee, J.U. Cho
Archives of Metallurgy and Materials.2017; 62(2): 1359. CrossRef
Torsion Property of the Structure Bonded Aluminum Foam Due to Impact
G.W. Hwang, J.U. Cho
Archives of Metallurgy and Materials.2017; 62(2): 1353. CrossRef
Experimental Study On Fracture Property Of Double Cantilever Beam Specimen With Aluminum Foam
Y.C. Kim, H.K. Choi, J.U. Cho
Archives of Metallurgy and Materials.2015; 60(2): 1151. CrossRef
Experimental Study On Fracture Property Of Tapered Double Cantilever Beam Specimen With Aluminum Foam
Y.C. Kim, S.S. Kim, J.U. Cho
Archives of Metallurgy and Materials.2015; 60(2): 1459. CrossRef
Processing Methods for the Preparation of Porous Ceramics
Rizwan Ahmad, Jang-Hoon Ha, In-Hyuck Song
Journal of Korean Powder Metallurgy Institute.2014; 21(5): 389. CrossRef
Effect of valeric acid on the agglomeration of zirconia particles and effects of the sintering temperature on the strut wall thickness of particle-stabilized foam
Rizwan Ahmad, Jang-Hoon Ha, In-Hyuck Song
Journal of the European Ceramic Society.2014; 34(5): 1303. CrossRef

The Electric and Thermal Properties of Spark Plasma Sintered Bi_0.5Sb_1.5Te₃: Gil-Geun Lee, Young-Hoon Choi, Gook-Hyun Ha; J Korean Powder Metall Inst. 2012;19(4):285-290.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.285

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Abstract PDF: The present study was focused on the analysis of the electric and thermal properties of spark plasma sintered Bi_0.5Sb_1.5Te_3 thermoelectric material. The crystal structure, microstructure, electric and thermal properties of the sintered body were evaluated by measuring XRD, SEM, electric resistivity, Hall effect and thermal conductivity. The Bi_0.5Sb_1.5Te_3 sintered body showed anisotropic crystal structure. The c-axis of the Bi_0.5Sb_1.5Te_3 crystal aligned in a parallel direction with applied pressure during spark plasma sintering. The degree of the crystal alignment increased with increasing sintering temperature and sintering time. The electric resistivity and thermal conductivity of the Bi_0.5Sb_1.5Te_3 sintered body showed anisotropic characteristics result from crystal alignment.

Milling Behaviors of Al-B₄C Composite Powders Fabricated by Mechanical Milling Process: Sung-Mo Hong, Jin-Ju Park, Eun-Kwang Park, Min-Ku Lee, Chang-Kyu Rhee, Ju-Myoung Kim, Jin-Kyu Lee; J Korean Powder Metall Inst. 2012;19(4):291-296.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.291

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In the present work, Al-B_4C composite powders were fabricated using a mechanical milling process and its milling behaviors and mechanical properties as functions of B_4C sizes ( 100µm, 500 nm and 50 nm) and concentrations (1, 3 and 10 wt.%) were investigated. For achieving it, composite powders and their compacts were fabricated using a planetary ball mill machine and magnetic pulse compaction technology. Al-B_4C composite powders represent the most uniform dispersion at a milling speed of 200 rpm and a milling time of 240 minutes. Also, the smaller B_4C particles were presented, the more excellent compositing characteristics are exhibited. In particular, in the case of the 50 nm B_4C added compact, it showed the highest values of compaction density and hardness compared with the conditions of 100µm and 500 nm additions, leading to the enhancement its mechanical properties.

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Influence of high B4C contents on structural evolution of Al-B4C nanocomposite powders produced by high energy ball milling
Hao Guo, Yu Zhao, Songsong Xu, Junpeng Li, Naimeng Liu, Yang Zhang, Zhongwu Zhang
Ceramics International.2019; 45(5): 5436. CrossRef
Effect of B4C Content on the Sintering Characteristics of 6061Al-B4C Composite Powder
Jin-Ju Park, Sung-Mo Hong, Kyoung-Yeol Kim, Min-Ku Lee, Chang-Kyu Rhee, Won-Hyuk Rhee, Yang Kyu Lee
Journal of Korean Powder Metallurgy Institute.2013; 20(3): 215. CrossRef

A Study on Voltammetry System Design for Realizing High Sensitivity Nano-Labeled Sensor of Detecting Heavy Metals: Ju-Myoung Kim, Chang-Kyu Rhee; J Korean Powder Metall Inst. 2012;19(4):297-303.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.297

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Abstract PDF: In this study, voltammetry system for realizing high sensitivity nano-labeled sensor of detecting heavy metals was designed, and optimal system operating conditions were determined. High precision digital to analog converter (DAC) circuit was designed to control applied unit voltage at working electrode and analog to digital converter (ADC) circuit was designed to measure the current range of 0.1sim1000µA at counter electrode. Main control unit (MCU) circuit for controlling voltammetry system with 150 MHz clock speed, main memory circuit for the mathematical operation processing of the measured current value and independent power circuit for analog/digital circuit parts to reduce various noise were designed. From result of voltammetry system operation, oxidation current peaks which are proportional to the concentrations of Zn, Cd and Pb ions were found at each oxidation potential with high precision.

The Effect of Processing Conditions on the Gradient Pore Structure of Diatomite by Centrifugal Molding: Jang-Hoon Ha, Eun-Ji Oh, Rizwan Ahmad, In-Hyuck Song; J Korean Powder Metall Inst. 2012;19(4):304-309.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.304

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The purpose of our study was to develop the fabrication method of porous diatomite ceramics with a porosity gradient by centrifugal molding. The processing variables of centrifugal molding were derived from Stoke's law of sedimentation, which were the radius of the particles, the acceleration due to centrifugal molding and the dynamic viscosity of the slurry. And these could be controlled by ball-milling conditions, centrifugal conditions, and the addition of methyl cellulose, respectively. The effects of processing conditions on the gradient pore structure of diatomite were investigated by particle size analysis, scanning electron microscope, and mercury porosimeter.

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Effect of the processing conditions of reticulated porous alumina on the compressive strength
Chae-Young Lee, Sujin Lee, Jang-Hoon Ha, Jongman Lee, In-Hyuck Song, Kyoung-Seok Moon
Journal of the Korean Ceramic Society.2021; 58(4): 495. CrossRef
Preparation and characterization of alumina-coated silicon carbide supports
Jang-Hoon Ha, Sujin Lee, Syed Zaighum Abbas Bukhari, Jae Ryung Choi, Jongman Lee, In-Hyuck Song, Seung Jun Lee, Jaeho Choi
Ceramics International.2017; 43(12): 9481. CrossRef

Synthesis of Nanocrystalline BaTiO₃ Powder by the Combination of High Energy Ball Milling of BaCO₃-TiO₂ Mixture and Solid-State Reaction: Sung-Soo Ryu; J Korean Powder Metall Inst. 2012;19(4):310-316.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.310

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Nanocrystalline BaTiO_3 powder could be synthesized by solid-state reaction using the mixture which was prepared by a high energy milling process in a bead mill for BaCO_3 and nanocrystalline TiO_2 powders mixture. Effect of the milling time on the powder characteristic of the synthesized BaTiO_3 powder was investigated. Nanocrystalline BaTiO_3 with a particle size of 50 nm was obtained at 800°C. High tetragonal BaTiO_3 powder with a tetragonality(=c/a) of 1.009 and a specific surface area of 7.6m2/g was acquired after heat-treatment at 950°C for 2 h. High energy ball milling was effective in decreasing the reaction temperature and increasing the tetragonality.

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Enhancement of dielectric properties and microstructure control of BaTiO3 by seed-induced solid-state synthesis
Seong Hyeok Choi, Yoon-Seok Lee, Sang Heun Lee, Kyungki Beak, Seungchan Cho, Ilguk Jo, Yangdo Kim, Kyoung-Seok Moon, Moonhee Choi
Ceramics International.2023; 49(11): 17921. CrossRef
Major factors affecting the dielectric properties and reliability of solid stated reacted BaTiO3powders for capacitor
Seong Hyeok Choi, Yoon-Seok Lee, Hun Kwak, Hyeon Jin Jung, Minkee Kim, Seungchan Cho, Jun Hyeon Yoon, Ji Woo Choi, Min Seong Kim, Ji Hyeon Kim, Ilguk Jo, Yangdo Kim, Moonhee Choi
Journal of Asian Ceramic Societies.2022; 10(4): 713. CrossRef
Preparation of tetragonal barium titanate nanopowders by microwave solid-state synthesis
Haoyu Qian, Guisheng Zhu, Huarui Xu, Xiuyun Zhang, Yunyun Zhao, Dongliang Yan, Xianyong Hong, Yin Han, Zhenxiao Fu, Shiwo Ta, Aibing Yu
Applied Physics A.2020;[Epub] CrossRef
Facile Synthesis of Highly Dispersed Ultra-fine ZrC Powders by Carbothermal Reduction Method Using Nanosized ZrO2and Nanosized Graphite Powder Mixtures
Wha-Jun Lee, Sung-Soo Ryu
Journal of Korean Powder Metallurgy Institute.2013; 20(2): 100. CrossRef

Microstructural Feature and Aging Characteristics of Spray-Formed Cu-5Ni-10Sn Alloy: Dae-Gyun Roh, Hee-Soo Kang, Kyeong-Ho Baik; J Korean Powder Metall Inst. 2012;19(4):317-321.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.317

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In this study, Cu-5Ni-10Sn(wt%) spinodal alloy was manufactured by gas atomization spray forming, and the microstructural features and mechanical properties of Cu-5Ni-10Sn alloy have been investigated during homogenization, cold working and age-hardening. The spray formed Cu-5Ni-10Sn alloy consisted of an equiaxed microstructure with a mixture of solid solution alpha-(CuNiSn) grains and lamellar-structure grains. Homogenization at 800°C and subsequent rapid quenching formed a uniform solid solution alpha-(CuNiSn) phase. Direct aging at 350°C from the homogenized Cu-5Ni-10Sn alloy promoted the precipitation of finely distributed gamma' or gamma-(Cu,Ni)_3Sn phase throughout the matrix, resulting in a significant increase in microhardness and tensile strength. Cold working prior to aging was effective in strengthening Cu-5Ni-10Sn alloy, which gave rise to a maximum tensile strength of 1165 MPa. Subsequent aging treatment slightly reduced the tensile strength to 1000-1100 MPa due to annealing effects.

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Improved mechanical and thermophysical properties of additively manufactured Cu-Ni-Sn-P alloy by using aging treatment
Dong-Hoon Yang, Young-Kyun Kim, Sun-Hong Park, Kee-Ahn Lee
Journal of Alloys and Compounds.2021; 875: 160050. CrossRef
Effect of post-heat treatment on the thermophysical and compressive mechanical properties of Cu-Ni-Sn alloy manufactured by selective laser melting
Young-Kyun Kim, Sun-Hong Park, Kee-Ahn Lee
Materials Characterization.2020; 162: 110194. CrossRef
Corrosion behavior of novel Cu–Ni–Al–Si alloy with super-high strength in 3.5% NaCl solution
Jia-jun ZHU, San-hua LI, Lei-nuo SHEN, Wu-lin YANG, Zhou LI
Transactions of Nonferrous Metals Society of China.2017; 27(5): 1096. CrossRef

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