Characterization of the deformation and phase transformation behavior of VC-free and VC-containing FeMnSi-based shape memory alloys by in situ neutron diffraction

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

卷:703

Article

Leinenbach, C.¹  Arabi-Hashemi, A.¹  Lee, W. J.^1,2  Lis, A.^1,3  Sadegh-Ahmadi, M.¹  Van Petegem, S.⁴  Panzner, T.⁵  Van Swygenhoven, H.^4,6 

[1] Empa, Swiss Fed Labs Mat Sci & Technol, Uberlandstr 129, CH-8600 Dubendorf, Switzerland

[2] Korea Inst Ind Technol, Busan 618230, South Korea

[3] Osaka Univ, Grad Sch Engn, Div Mat & Mfg Sci, Suita, Osaka, Japan

[4] Paul Scherrer Inst, Swiss Light Source, CH-5232 Villigen, Switzerland

[5] Paul Scherrer Inst, Neutron Scattering Lab, NUM, CH-5232 Villigen, Switzerland

[6] Ecole Polytech Fed Lausanne, Neutrons & Xrays Mech Mat, IMX, CH-1012 Lausanne, Switzerland

关键词: FeMnSi;    Shape memory alloy;    Neutron diffraction;    Martensite;   

DOI  :  10.1016/j.msea.2017.07.077

来源: Elsevier

【 摘 要 】

The stress-induced fcc-austenite to hcp-martensite transformation in the iron based shape memory alloy (SMA) Fe-17Mn-5Si-10Cr-4Ni with and without VC precipitates is investigated by in-situ neutron diffraction measurements upon uniaxial loading and unloading. Based on experimentally derived elastic moduli the critical resolved shear stress (CRSS) for the fcc to hcp phase transformation was calculated. VC precipitates promote the martensite transformation by shifting the CRSS from 152 MPa to 85 MPa. A nearly perfect plastic behavior is found for the (220) grains with a high Schmid factor of 0.47. While (220), (111) and (200) oriented grains exhibit a phase transformation, (311) grains plastically deform solely by slip. During plastic deformation a load redistribution from soft behaving (220) grains to hard behaving (200) orientated grains takes place. The presence of VC precipitates leads to a broadening of the stress interval at which a martensite transformation is induced. This is explained by spatially heterogeneously distributed martensite transformation temperatures which are caused by VC precipitates. The microstructural reason for pseudo-elasticity is found to be a combination of back transformation from hcp to fcc and a reversible motion of Shockley partial dislocations.

【 授权许可】

Free