Macroscopic inhomogeneous deformation behavior arising in single crystal Ni–Mn–Ga foils under tensile loading. (December 2016)

• Record Type: Journal Article
• Authors: Murasawa, Go; Yeduru, Srinivasa R.; Kohl, Manfred
• Is Part Of: Optics and lasers in engineering. Volume 87(2016)
• Page Start: 139
• Page End: 145
• Publication Date: 2016-12
• Subjects: Single-crystal Ni–Mn–Ga foil -- Inhomogeneous deformation behavior -- Thermo-mechanical training -- Digital image correlation; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2015.12.014
• Languages: English
• ISSNs: 0143-8166

Abstract

Abstract: This study investigated macroscopic inhomogeneous deformation occurring in single-crystal Ni–Mn–Ga foils under uniaxial tensile loading. Two types of single-crystal Ni–Mn–Ga foil samples were examined as-received and after thermo-mechanical training. Local strain and the strain field were measured under tensile loading using laser speckle and digital image correlation. The as-received sample showed a strongly inhomogeneous strain field with intermittence under progressive deformation, but the trained sample result showed strain field homogeneity throughout the specimen surface. The as-received sample is a mainly polycrystalline-like state composed of the domain structure. The sample contains many domain boundaries and large domain structures in the body. Its structure would cause large local strain band nucleation with intermittence. However, the trained one is an ideal single-crystalline state with a transformation preferential orientation of variants after almost all domain boundary and large domain structures vanish during thermo-mechanical training. As a result, macroscopic homogeneous deformation occurs on the trained sample surface during deformation. Highlights: Strains are measured using laser speckle and DIC for single-crystal NiMnGa. NiMnGa deformation behavior drastically changes by thermo-mechanical training. NiMnGa domain structure would vanish by thermo-mechanical training.