High elastic strain in shape memory alloys exhibiting significant lattice softening -- critical phenomenon under stress

常规金属和合金的弹性极限小于1%，尽管通过理论计算获得的理想值为10%或更高。我们发现，Fe 3 Pt和Fe-Pd合金表现出超过6%的弹性应变时，应力施加在[001]方向。这些合金表现出弱的一级马氏体相变，并且在接近相变温度时发生弹性常数C'的软化。通过压应力下的中子衍射实验，我们证实了高弹性应变是由于晶格常数的连续变化。此外，我们发现，相变应变，这是一级马氏体相变的特征，随着在[001]方向上的压应力的增加而消失。

Elastic limits of conventional metals and alloys are smaller than 1%, although the ideal values obtained by theoretical calculations is 10% and higher. We found that Fe3Pt and Fe-Pd alloys exhibits elastic strain of more than 6% when stress is applied in the [001] direction. These alloys exhibit weak first order martensitic transformations and softening in elastic constant C' occurs on approaching the transformation temperature. We confirmed that the high elastic strain is due to continuous change in lattice parameter by neutron diffraction experiments under compressive stresses. Moreover, we found that the transformation strain, which is characteristic feature of first order martensitic transformations, disappears as the compressive stress in the [001] direction increases.