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

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