Martensitic and austenitic local structures in a bcc Ti-Zr-Hf-Co-Ni-Cu-Pd related high entropy shape-memory alloy

The idea of producing a crystalline alloy with good properties based on a heavy mix of elements in near-equiatomic stoichiometry, leading to the discovery of High Entropy Alloys (HEA) was completely new and pushed the boundaries of properties understanding beyond what was known so far from one- and two-element based alloys. In the context of high entropy shape-memory alloys related to Ti-Zr-Hf-Co-Ni-Cu-Pd, and its precursors, X-ray absorption spectroscopy (XAS) will be used to investigate bond distances between selected pair of elements. The structural phase transition between martensite and austenite states will be analyzed, i.e. the fundamental mechanism on which shape-memory-effects are based. Finally, a broader comparison of this system in its austenitic phase will be carried out with data already acquired in previous experiments on hcp-based (Ti-Hf-Zr-Al-Sc) and fcc-based (Al-Cr-Co-Cu-Fe-Ni) systems, for a better understanding of crystal structure properties in HEAs altogether.