Determination of the martensitic transformation features in a high-entropy shape-memory (TiHfZr)74(NbTa)26 alloy

Being developed for medical applications, the (TiHfZr)74(NbTa)26 alloy is a new high-entropy shape memory alloy (HE-SMA); composed of five chemical elements, it exhibits a reversible martensitic transformation (MT) under mechanical loading. As some medical applications may contain a reduced number of grains, a micromechanical analysis in the bulk of the material is mandatory. Elastic constants of this alloy have been determined in a previous experiment (MA5410). So, the aim of this proposal is to determine the MT features of this new HESMA at the grain scale. In that proposal, Diffraction Contrast Tomography (DCT) and topotomogrpaphy (TT) will serve to detect the occurrence of MT and identify martensite variants during in-situ tensile test. Coupling with 3D-XRD and S-3DXRD will allow calculating the critical shear stress of MT. All the experimental data are mandatory for modelling and will serve as input data of a micromechanical finite element model to design structural applications.