Structural and Martensitic Transformation of Heusler Mn-Ni-Sn Alloys

Abstract

The improved functional stability of shape memory alloys, which undergo a reversible martensitic transition, is essential to their applications and remains a matter of critical research based on advanced shape memory technology. In this paper, the microstructure, phase structure and martensitic transformation of Heusler Mn50Ni50−xSnx (x= 5, 7.5 and 10) alloys studied by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. The results show that the structure of martensite phase is identified to be 14M monoclinic structure, while, the austenite phase is with L21 cubic structure. The martensitic transition temperatures are found to decrease with the increase in Sn content due to the decrease in valence electron concentration ((e/a) ratio).