Shape Memory Effect in Ferromagnetic Ni‐Mn‐Ga Alloy

Abstract

The martensitic magnetothermoelastic transformation induced by a magnetic field in FSMA has been studied. It has been observed that the shape memory effect is associated with the reversible magnetic field‐induced martensite at higher temperatures. It has been noted that upon cooling from the high temperature austenite parent phase the ferromagnetic shape memory alloys exhibit transition from paramagnetism to ferromagnetism. The Ni‐25Mn‐25Ga (at%) shows the thermomechanical martensitic transformation. The micrograph shows the martensitic transformation of the alloy that strongly depends on the applied magnetic field. The mechanisms of the magnetic microstructure causes the martensite bands, which run diagonally from left to right in the micrograph, have been observed. It is proposed that the FSMAs are very promising candidates for biomedical applications as the new smart material.

Keywords:

• smart materials
• ferromagnetic shape memory alloys
• electromagnetic actuator
• hysteresis curve
• magnetic band domains
• saturation magnetization
• martensite
• austenite

Acknowledgments

One of the authors (MM) thank the Management and the Principal of Thiagarajar College of Engineering for their support and assistance to carry out this work and he thanks Prof. J.G.Li of School of Materials Science and Engineering, Shanghai Jiao Tong University, PR China for providing the Gallium ingot.