Phase Transition from BCC Phase in Fe-Mn-based Alloys with Anomalously Small Entropy Change

研究了包括Fe-Mn-Al基合金在内的铁基合金从α相(Bcc)到伽马相(Fcc)的马氏体相变。热力学分析发现，这种相变是由于α相的磁性被抑制而发生的。研究还发现，Ni的加入使合金发生了热弹转变。此外，Fe-Mn-Al-Ni合金在较宽的温度范围内表现出超弹性。超弹应变强烈依赖于显微组织，晶粒度控制是影响超弹应变的重要因素之一。

The martensitic transformation from the alpha phase (BCC) to the gamma phase (FCC) in Fe-based alloys including Fe-Mn-Al-based alloy was investigated. It was found from the thermodynamic analysis that this phase transformation can occur due to the suppression of the magnetism of the alpha phase. It was also found that the thermoelastic transformation is obtained by the addition of Ni. Moreover, the Fe-Mn-Al-Ni alloy exhibits the superelasticity in a wide temperature range. The superelastic strain was strongly dependent on the microstructure and the grain size control was one of the most important factors.