It was shown already [1,2], that TiZrHfCoNiCu high entropy alloys undergo martensitic transformation, which is accompanied by shape memory behavior in a wide temperature range, including elevated temperatures. The latter allows including them into high temperature shape memory alloys (HTSMA) family. Comparing with other HTSMA , these novel multi-component materials possess high strength and diffusion stability that result in stable and complete shape recovery [1,2]. The origin of this is related to the peculiar crystal and electronic structure that has been noticed already [1,4]. The aim of the present report is to show that structural peculiarities mentioned above are, in fact, triclinic distortions of the crystal structure that exist already in the high temperature (austenite) B2 phase, which carries these distortions into B19`martensite. It will be described how these distortions result from specific interatomic interaction that takes place in (TiZrHf)50(CoNiCu)50 intermetallic compounds and, in their own turn, ensure two-fold increase in yield strength, comparing to TiNi prototype, and, as a result, exhibit complete and stable shape memory behavior even at elevated temperatures.
Keywords: crystal and electronic structure, martensitic transformation, elevated temperatures, high entropy shape memory alloys