Theoretical Analysis of Hysteresis and Characteristic Transition Temperatures of Iron-Based Memory Metals

The correlation between valence electrons per atom (ev/a) and the characteristic transition temperatures of quaternary and quinary Fe-based shape memory alloys (SMAs) is investigated. Regression equations relating their transformation temperatures (Ms, As) to composition and ev/a are obtained. On adding alloying elements to the SMAs, their transformation temperatures get altered and this is correlated to their ev/a ratio. Three distinct trends between the ev/a ratio and transformation temperatures are found. The correlation between the transformation hysteresis and the atom diameter of the alloying elements is also analysed.