Dependence of Transformation Temperatures of NiTi‐based Shape‐Memory Alloys on the Number and Concentration of Valence Electrons

Abstract Dependence of transformation temperatures of ternary and quaternary NiTi‐based shape memory alloys on the number ( e v / a ) and concentration ( c v ) of valence electrons is investigated. Two distinct trends of transformation temperatures with respect to the number of valence electrons per atom are found depending on whether e v / a = 7 or e v / a ≠ 7. Clear correlations between transformation temperatures and c v exist. M s and A s decrease consistently from 900 to −100 °C, and 950 to −30 °C, respectively, with increasing c v from 0.145 to 0.296. The relationship of electron concentration on the elastic moduli of the NiTi‐based alloys is discussed. The possible influence of the atomic size of alloying elements on transformation hysteresis is introduced.