Thermal and structural analysis of Ni 50 Mn 50− x In x shape memory alloys

Abstract

In the present study, the Ni50Mn50−xInx (x = 12, 13 and 14 at.%) shape memory alloys were obtained by rapid solidification. The martensitic transformation and the solidification structures of these alloys were carried out by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry, respectively. The experimental results showed that the crystalline structure of martensite in the In12 and In13 ribbons was identified as a 10M monoclinic structure, although the austenite has a cubic L21 structure for the In14 alloy. The martensitic transformation start temperature Ms decreases progressively with the increasing In content. The Ni content is mainly responsible for the adjustment in martensite transformation behavior in these shape memory alloys. Finally, the control of the valence electron by atom (e/a) determines the practical properties of these alloys at room temperature and makes it possible to create the alloys that can be candidates for various uses, such as sensors, refrigerants for magnetic refrigeration and actuators