The effect of high-pressure torsion on the microstructure and outstanding pseudoelasticity of a ternary Fe-Ni-Mn shape memory alloy

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:802

Article

Koohdar, Hamidreza¹  Nili-Ahmadabadi, Mahmoud^2,3  Kalahroudi, Faezeh Javadzadeh²  Jafarian, Hamid Reza¹  Langdon, Terence G.⁴ 

[1] Iran Univ Sci & Technol IUST, Sch Met & Mat Engn, Tehran, Iran

[2] Univ Tehran, Sch Met & Mat Engn, POB 14395-731, Tehran, Iran

[3] Univ Tehran, Sch Met & Mat Engn, Ctr Excellence High Performance Mat, Tehran, Iran

[4] Univ Southampton, Dept Mech Engn, Mat Res Grp, Southampton SO17 1BJ, Hants, England

关键词: High-pressure torsion;    Microstructural evolution;    Pseudoelastic behavior;    Strain hysteresis;    Ternary Fe-Ni-Mn shape memory alloy;   

DOI  :  10.1016/j.msea.2020.140647

来源: Elsevier

【 摘 要 】

Experiments were conducted to examine the effect of high-pressure torsion (HPT) processing on the microstructure and pseudoelastic behavior of a ternary Fe-10Ni-7Mn (wt.%) shape memory alloy in both the solution annealed and intercritically-annealed conditions. X-ray diffraction (XRD) patterns and electron backscatter diffraction (EBSD) analyses showed that the initial microstructure of the alloy in the solution-annealed condition was a fully lath alpha'-martensite which partially transformed to a strain-induced austenite (alpha'->gamma) by HPT processing. Also, the austenite formed in the dual phase (alpha'+gamma) specimens after intercritical annealing treatment at 600 degrees C for 7.2 ks underwent a gamma ->epsilon ->alpha' transformation during subsequent HPT processing such that a multi-phase microstructure was formed consisting of alpha'-martensite, austenite and epsilon-martensite. The HPT processing led to a significant increase in the microhardness value to similar to 690 Hv due to a high density of dislocations and the associated grain refinement of the microstructure. Cyclic loading-unloading tensile tests at room temperature revealed a strain hysteresis and pseudoelastic behavior in the HPT-processed specimens with different initial microstructures. Outstanding pseudoelasticity values of about 67% and 75% were obtained at the fourteenth loading-unloading cycle after 20 HPT turns in the solution-annealed and intercritically-annealed specimens, respectively.

【 授权许可】

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