Stress-induced martensitic transformation, twin boundary mobility and elastic properties of vapor deposited Fe70Pd30 ferromagnetic shape memory alloy thin films

Within an in situ study, we explore mechanical properties of Fe70Pd30 ferromagnetic shape memory alloy thin films. While performing tensile measurements on freestanding films, we accomplish to observe the appearance of twin boundaries due to the stress-induced austenite–martensite transition. Changing distances between twin boundaries during further straining indicate the growth of single variant regions at the expense of others. Young’s moduli of 2.2–8.3 GPa were determined. For comparison, temperature dependent surface acoustic waves were applied on as-deposited films exhibiting much higher Young’s moduli. These findings are discussed considering the influence of phase stability and phase transition characteristics.

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