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Kinetic grain growth, shape memory and corrosion behavior of two Cu-based shape memory alloys after thermomechanical treatment

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Transactions of Nonferrous Metals Society of China 2013年第10期23卷 2896-2904页

作者： Ahmad ostovari MOGHADDAM Mostafa KETABCHI Reza BAHRAMI Department of Mining and Metallurgical Engineering Amirkabir University of Technology

Metallurgical and mechanical properties along with shape memory and corrosion behavior of Cu-11.8% AI-3.7% Ni-1 %Mn and Cu-11% A1 5.6% Mn shape memory alloys （SMAs） were comparatively studied. The influence of grain refinement on the properties was studied by optical microscopy （OM）, scanning electron microscopy （SEM）, differential scanning calorimetry （DSC）, potentiodynamic polarizations and bend and tensile tests. Static recrystallization and kinetic grain growth show a rapid recrystallization in the first 15 s of annealing at 800℃ followed by grain growths. The minimum grain sizes obtained after 15 s are 90 and 260 μm for Cu-A1-Ni-Mn and Cu-A1-Mn, respectively. Tensile tests show typical three-stage curves for both alloys, and it is seen that alloys exhibit high fracture stress and strain after grain refinement. Microstructural observations show zig-zag morphology of β 1martensite in the Cu-A1-Ni-Mn and coexistence of β1 and y1 in the Cu-A1-Mn, which were confirmed by differential scanning calorimetry results. The shape memory ratios （17） of the alloys before thermomechanieal treatment, and after thermomechanical annealing at 800 ℃ for different time up to 15 min followed by water quenching, were evaluated. In addition, corrosion behavior of alloys after grain refinement was analyzed by means of potentiodynamic polarization measurements. The results showed that the anodic reactions were dominated by dissolution of copper, and Cu-AI-Ni-Mn alloy exhibits a better corrosion resistance than Cu-A1-Mn alloy.

关键词： shape memory alloys (SMAs) grain refinement corrosion shape memory properties

Additive manufacturing of high entropy alloys:A practical review

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Journal of Materials Science & Technology 2021年第18期77卷 131-162页

作者： Ahmad ostovari Moghaddam Nataliya A.Shaburova Marina N.Samodurova Amin Abdollahzadeh Evgeny A.Trofimov Department of Materials Science.Physical and Chemical Properties of Materials.South Ural State University 76 Lenin AveChelyabinsk454080Russian Federation Department of Metal Forming South Ural State University76 Lenin AveChelyabinsk.454080Russian Federation Department of Materials Science and Engineering Faculty of EngineeringShahid Chamran University ofAhvazAhvazIran

The novel idea of alloying,which is based on the utilization of multiple principal elements in high concentrations,has created a novel class of promising materials called high entropy alloys(HEAs).So far,several HEAs with outstanding properties beyond those of conventional alloys have been discovered,and new superior high-entropy alloys are still expected to be developed in the ***,the fabrication process of HEAs through conventional manufacturing techniques suffers from significant limitations due to the intrinsic requirements of *** manufacturing(AM),on the other hand,has provided new opportunities for fabricating geometrically complex HEAs with the possibility of in situ tailoring of their microstructure *** the growing interest in AM of HEAs during most recent years,this review article aims at providing the state of the art in AM of *** describes the feedstock requirements for laser based AM ***,a comprehensive picture of the current state of nearly all HEAs processed by laser metal deposition(LMD),selective laser melting(SLM)and selective electron beam melting(SEBM)is *** attention is paid to the features of AM derived microstructures along with their outstanding properties and underlying mechanisms for various material processing *** AM of interstitial solute hardening HEAs,HEA matrix composites as well as non-beam based AM of HEAs will also be *** post-AM treatments and the strategies to fabricate defect-free HEAs are ***,a conclusion of current state and future prospects of additive manufacturing of HEAs will be presented.

关键词： High entropy alloys Additive manufacturing Microstructure Mechanical properties

Phase formation and thermoelectric properties of Zn_(1+x)Sb binary system

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Transactions of Nonferrous Metals Society of China 2021年第3期31卷 753-763页

作者： Ahmad ostovari MOGHADDAM Evgeny TROFIMOV Ting ZHANG Jordi ARBIOL Andreu CABOT Department of Materials Science Physical and Chemical Properties of MaterialsSouth Ural State University76 Lenin AveChelyabinsk454080Russia Catalan Institute of Nanoscience and Nanotechnology(ICN2) Consejo Superior de Investigaciones Científicas(CSIC)and Barcelona Institute of Science and Technology(BIST)Campus Autonomous University of Barcelona(UAB)Bellaterra08193 BarcelonaSpain Catalonia Institute for Energy Research-IREC Sant Adriàde Besòs08930 BarcelonaSpain Catalan Institution for Research and Advanced Studies-ICREA Pg.Lluís Companys 2308010 BarcelonaSpain

The phase formation and thermoelectric(TE)properties in the central region of the Zn−Sb phase diagram were analyzed through synthesizing a series of Zn_(1+x)Sb(x=0,0.05,0.1,0.15,0.25,0.3)materials by reacting Zn and Sb powders below the solidus line of the Zn−Sb binary phase diagram followed by furnace *** this process,the nonstoichiometric powder blend crystallized in a combination of ZnSb andβ-Zn4Sb3 ***,the materials were ground and hot pressed to form dense ZnSb/β-Zn4Sb3 *** traces of Sb and Zn elements or other phases were revealed by X-ray diffraction,high resolution transmission electron microscopy and electron energy loss spectroscopy *** thermoelectric properties of all materials could be rationalized as a combination of the thermoelectric behavior of ZnSb andβ-Zn4Sb3 phases,which were dominated by the main phase in each ***1.3Sb composite exhibited the best thermoelectric *** was also found that Ge doping substantially increased the Seebeck coefficient of Zn1.3Sb and led to significantly higher power factor,up to 1.51 mW·m−1·K−2 at 540 ***,an exceptional and stable TE figure of merit(ZT)of 1.17 at 650 K was obtained for Zn1.28Ge0.02Sb.

关键词： Zn_(1+x)Sb ZnSb/β-Zn4Sb3 composite thermal stability thermoelectric properties