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Kinetic characteristics of liquid phase sintering of mechanically activated W-15wt%Cu powder

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Journal of University of Science and Technology Beijing 2006年第4期13卷 338-345页

作者： Zhigang Li Chengchang Jia Yuntao He Liliang Chen Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

The kinetic characteristics of W grain growth operated by diffusion controlled Oswald ripening （DOR） during liquid phase sintering were studied. A liquid phase sintering of W-15wt%Cu was carried out by pushing compacts into a furnace at the moment when the temperature increased to 1340℃ for different sintering times. The results show that liquid phase sintering produces the compacts with considerably low relative density and inversely, rather high homogeneity. On the basis of the data extracted from the SEM images, the kinetic equation of W grain growth, G^n = G0^n ＋ kt, is determined in which the grain growth exponent n is 3 and the grain growth rate constant k is 0.15 μm^3/s. The cumulative normalized grain size distributions produced by different sintering times show self-similar. The cumulative distribution function is extracted from the curves by non-linear fitting. In addition, the sintering kinetic characteristics of W-15wt%Cu compacts were also investigated.

关键词： liquid phase sintering mechanical alloying grain growth kinetics W-Cu alloy

A Novel,Amorphous,Non-equiatomic FeCrAlCuNiSi High-Entropy Alloy with Exceptional Corrosion Resistance and mechanical Properties

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Acta Metallurgica Sinica(English Letters) 2020年第8期33卷 1057-1063页

作者： Xigang Yang Yun Zhou Ruihua Zhu Shengqi Xi Cheng He Hongjing Wu Yuan Gao State Key Laboratory for mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi'an 710049China School of Medical Information and Engineering Southwest Medical UniversityLuzhou 646000China

The exceptional corrosion resistance and mechanical properties of high-entropy metallic glasses(HE-MGs)are highly desirable for diverse critical applications.However,a long-standing problem of these alloys is that their alloy design approaches are based on limited equiatomic or near-equiatomic ratios.In this study,a novel senary alloy(non-equiatomic Fe3 Cr2 Al2 CuNi4 Si5)with amorphous structure was prepared.This alloy exhibited exceptional corrosion resistance and Vickers hardness as high as^1150 Hv at room temperature.The processing route involved amorphous powder molding via a mechanical alloying and ultrahigh pressure consolidation technique,resulting in an optimal microstructure of amorphous structure with nanoparticles uniformly distributed in the matrix alloy.This approach can effectively inhibit the crystallization of amorphous structure,thus providing a general pathway for manufacturing next-generation non-equiatomic HE-MGs with both exceptional corrosion resistance and strength.

关键词： alloying Metallic glasses Corrosion resistance mechanical alloying High-entropy metallic glasses

Powder metallurgy of high-entropy alloys and related composites: A short review

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International Journal of Minerals,Metallurgy and Materials 2021年第6期28卷 931-943页

作者： Bo-ren Ke Yu-chen Sun Yong Zhang Wen-rui Wang Wei-min Wang Pei-yan Ma Wei Ji Zheng-yi Fu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Beijing Advanced Innovation Center of Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing 100083China School of mechanical Engineering University of Science and Technology BeijingBeijing 100083China School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China School of Chemistry Chemical Engineering and Life ScienceWuhan University of TechnologyWuhan 430070China

High-entropy alloys(HEAs)have attracted increasing attention because of their unique properties,including high strength,hardness,chemical stability,and good wear resistance.Powder metallurgy is one of the most important methods used to fabricate HEA materials.This paper introduces the methods used to synthesize HEA powders and consolidate HEA bulk.The phase transformation,microstructural evolution,and mechanical properties of HEAs obtained by powder metallurgy are summarized.We also address HEA-related materials such as ceramic–HEA cermets and HEA-based composites fabricated by powder metallurgy.

关键词： high-entropy alloys powder metallurgy mechanical alloying consolidation

Corrosion Behavior of Ψ and β Quasicrystalline Al–Cu–Fe Alloy

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Acta Metallurgica Sinica(English Letters) 2015年第9期28卷 1117-1122页

作者： Alvaro Torres Sergio Serna Cristobal Patio Gerardo Rosas Facultad de Ciencias Químicas e Ingeniería P.A. Ing.Mecnica UAEM Av. Universidad 1001 Col. Chamilpa62210 Cuernavaca Mor. Mexico Centro de Investigación en Ingeniería y Ciencias Aplicadas UAEM Av. Universidad 1001 Col. Chamilpa62210 Cuernavaca Mor. Mexico Facultad de Ingeniería Universidad Autónoma del CarmenCampus Ⅲ Avenida Central S/N Esq. con Fracc. MundoMaya C.P. 24115 Ciudad del Carmen Campeche Mexico Instituto de Investigaciones Metalurgicas UMSNH Edificio U. Ciudad Universitaria Morelia Mich. 58000 Mexico

Two nanostructured A1-Cu-Fe alloys, A164Cu24Fe12 and A162.5Cu25.2Fe12.3, have been studied. Icosahedral quasicrystalline （ψ） A164CH24FeI2 and crystalline cubic （ β） AI62.sCu25.2Fe12.3 cylindrical ingots were first produced using normal casting techniques. High-energy mechanical milling was then conducted to obtain β icosahedral and β intermetallic nanostructured powders. Electrochemical impedance spectroscopy, linear polarization resistance, and potentiodynamic polarization were used to investigate the electrochemical corrosion characteristics of the powders in solutions with different pH values. Current density （icorr）, polarization resistance （Rp）, and impedance modulus （121） were determined. The results showed that regardless of pH value, increasing the solution temperature enhanced the corrosion resistance of the both phases. However, the electrochemical behavior of the phase indicated that its stability depends on the submerged exposure time in neutral and alkaline environments. This behavior was related to the type of corrosion products present on the surfaces of the particles along with the diffusion and charge-transfer mechanisms of the corrosion process.

关键词： Nano-quasicrystalline AI-Cu-Fe alloy mechanical alloying Corrosion

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

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Acta Metallurgica Sinica(English Letters) 2015年第7期28卷 809-816页

作者： Chao Yang He-Fei Huang Massey de los Reyes Long Yan Xing-Tai Zhou Tian Xia De-Liang Zhang Shanghai Institute of Applied Physics Chinese Academy of Science (CAS) Institute of Materials Engineering Australian Nuclear Science and Technology Organisation State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University

Silicon carbide nanoparticle-reinforced nickel-based composites（Ni–Si CNP）,with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy（TEM） was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening（Orowan effects） and particle strengthening（Hall–Petch effects）.For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.

关键词： Ni-SiCNP composite mechanical alloying Spark plasma sintering Transmission electron microscopy Tensile test

Corrosion behavior of three Ag–50Cu alloys prepared by different processes in NaCl solutions

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Rare Metals 2017年第1期36卷 61-68页

作者： Zhong-Qiu Jia Qiu-Ying Liang Qiu-Yue Tian Zhong-Qiu Cao Yan Wang College of Chemistry-and Chemical Engineering Shenyang Normal University Shenyang 110034 China

Corrosion behavior of two nanocrystalline bulk Ag–50Cu alloys and one coarse-grained counterpart prepared by liquid-phase reduction(LPR), mechanical alloying(MA) and powder metallurgy(PM) methods,respectively, were investigated in Na Cl solutions. They were finished by means of PARM273 A and M5210 electrochemical apparatus through potentiodynamic polarization method and electrochemical impedance spectroscopy(EIS) technique. The results show that corrosion rates of three Ag–50Cu alloys increase with the increment of Na Cl solution concentrations. Corrosion rates of LPRAg–50Cu alloy are a little higher than those of PMAg–50Cu alloy,but evidently lower than those of MAAg–50Cu alloy. The difference in corrosion rates is attributed to the large reduction in the grain size and homogeneous microstructure of nanocrystalline alloys. Passive current densities decrease and afterward increase for PMAg–50Cu alloy,decrease for MAAg–50Cu alloy, and increase for LPRAg–50Cu alloy with the increment of Na Cl solution concentrations. After the grain sizes are refined, passive current densities become lower.

关键词： Copper alloys Corrosion Corrosion rate Corrosive effects Electrochemical corrosion Electrochemical impedance spectroscopy Electrochemistry Grain size and shape mechanical alloying Nanocrystals Powder metallurgy Reduction Silver Silver alloys

Characterization of NbSi_2–Al_2O_3 nanocomposite coatings prepared with plasma spraying mechanically alloyed powders

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International Journal of Minerals,Metallurgy and Materials 2015年第7期22卷 748-754页

作者： Zohreh Yazdani Fathallah Karimzadeh Mohammad-Hasan Abbasi Abbas Amini Department of Materials Engineering Isfahan University of Technology

The present study characterized NbSi2-Al2O3 nanocomposite powders plasma-sprayed on Ti-6Al-4Vsubstrates. The powders were agglomerated to obtain suitable particle sizes for spraying. The agglomerated powders were then plasma-sprayed using atmospheric plasma spraying. The structural transformations of the powders along with the morphological and mechanical changes of the coatings were examined by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and hard- ness testing. The results showed that after plasma spraying, the grain size increased, and the lattice strain decreased. However, the grain size of this compound after spraying was still in the nanometer range. The coating was uniform and exhibited good adhesion to the substrate. The microhardness and fracture toughness of the nanocomposite coating were higher than those of a nanostructured NbSi2 coating.

关键词： nanocomposites coatings plasma spraying mechanical alloying

Effect of process parameters on the density and porosity of laser melted AlSi10Mg/SiC metal matrix composite

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Frontiers of mechanical Engineering 2018年第4期13卷 520-527页

作者： Omotoyosi H. FAMODIMU Mark STANFORD Chike F. ODUOZA Lijuan ZHANG Faculty of Science and Engineering School of Engineering Telford Campus University of Wolverhampton WV1 1LY Wolverhampton UK

Laser melting of aluminium alloy-AlSi10Mg has increasingly been used to create specialised products in various industrial applications, however, research on utilising laser melting of aluminium matrix composites in replacing specialised parts have been slow on the uptake. This has been attributed to the complexity of the laser melting process, metal/ceramic feedstock for the process and the reaction of the feedstock material to the laser. Thus, an understanding of the process, material microstructure and mechanical properties is important for its adoption as a manufacturing route of aluminium metal matrix composites. The effects of several parameters of the laser melting process on the mechanical blended composite were thus investigated in this research. This included single track formations of the matrix alloy and the composite alloyed with 5% and 10% respectively for their reaction to laser melting and the fabrication of density blocks to investigate the relative density and porosity over different scan speeds. The results from these experiments were utilised in determining a process window in fabricating near-fully dense parts.

关键词： selective laser melting additive manufacturing mechanical alloying powder metallurgy aluminium metal matrix composite

Thermoelectrical properties of(FeNi)_xCo_(4-x)Sb_(12) prepared by MA-SPS

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Journal of University of Science and Technology Beijing 2008年第3期15卷 272-275页

作者： Kegao Liu Jiuxing Zhang School of Materials Science and Engineering Shandong Jianzhu University Jinan 250101 China School of Materials and Engineering Beijing University of Technology Beijing 100022 China

Bulk skutterudite （FeNi）xCo4-xSbl2 with x varying from 0.05 to 1.0 were prepared by mechanical alloying and spark plasma sintering （MA-SPS）. The phases of the samples were analyzed by X-ray diffraction, and their thermoelectrical properties were tested by electrical constant instrument and laser thermal constant instrument. The experimental results show that bulk （FeNi）xCo4-xSb12 have the characteristic of typical semiconductor electricity. The addition of FeNi improves the electrical properties to a large extent; the samples of bulk （FeNi）xCo4-xSbl2 （x = 0.05-1.0） are n-type semiconducting materials; the increase of FeNi content can decrease the absolute value of Seebeck coefficient and therefore decrease the ZT value; FeNi with a higher content when x 〉 0.5 leads to an evident increase in thermal conductivity and also a decrease in ZT value. In general, for ZT value, the optimal added content of FeNi is 0.25-0.5 and the maximum ZT value is 0.2467 when x = 0.5 at 500℃.

关键词： thermoelectrical materials thermoelectrical properties skutterudite mechanical alloying spark plasma sintering