Critical point of martensitic transformation under stress in an Fe-31.2Pd (at.%) shape memory alloy

We have examined the transformation strain, Delta epsilon, in the [001] direction of an Fe-31.2Pd (at.%) shape memory alloy under compressive stress applied in the same direction. When the stress is absent, the alloy exhibits a cubic to tetragonal martensitic transformation at 230K with |Delta epsilon| of 1.4%. As the stress increases, the transformation temperature increases linearly and |Delta epsilon| decreases linearly and vanishes at 40MPa (280K). This point is the critical point of this transformation at which the first-order nature disappears, and the critical exponent beta is evaluated to be 0.47 +/- 0.04.