Experimental Study on the Anisotropic Stress-Strain Behavior of Polycrystalline Ni-Mn-Ga in Directional Solidification

• Published in: Journal of materials engineering and performance Vol. 25; no. 3; pp. 1056 - 1061
• Main Authors: Teng, Yao, Shi, Tao, Zhu, Yuping, Li, Zongbin, Deng, Tao, Bai, Guonan
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2016
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Engineering Design; Materials Science; Quality Control; Reliability; Safety and Risk; Tribology; ferromagnetic shape memory alloy; stress-strain curves; directional solidification; anisotropy
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-016-1920-z

A polycrystalline Ni-Mn-Ga ferromagnetic shape memory alloy produced by directional solidification is the subject of this research paper. The compressive stress-strain curves of the material for different cutting angles to the solidification direction are tested. The martensite Young’s modulus, macroscopic reorientation strain, and phase transition critical stress are analyzed experimentally. The results show that mechanical behaviors in the loading-unloading cycle of the material present nonlinear and anisotropic characteristics, which are all closely related to the material’s orientation to the solidification direction. The martensite Young’s modulus, macroscopic reorientation strain, and phase transition critical stress achieve maximum values in the solidification direction. A 50° orientation to the solidification direction is the cut-off direction of the mechanical properties, where the martensite Young’s modulus and reorientation start critical stress reach minimum values. The present study is expected to provide sound guidance for practical applications.