Synthesis and effect of aging treatment on the properties of Ti16.67Zr16.67Hf16.67Ni25Co10Cu15 high-entropy shape memory alloy

Synthesis and the effect of prolonged aging time, for 1, 10, and 20 h at 500 °C, on microstructure, shape memory effect, mechanical, and electrochemical corrosion behavior of Ti16.67Zr16.67Hf16.67Ni25Co10Cu15 high-entropy shape memory alloy (HESMA) were investigated. This alloy was developed by an arc melting process and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), a thermomechanical analyzer (TMA), nanoindentation, and Gamry Potentiostat. SEM and XRD results showed a stable microstructure during aging treatment. AFM results represented no significant change in RMS roughness and Ra roughness value. TMA results elaborated the stable transformation temperatures and thermal hysteresis. Nanoindentation and micro Vickers’ results showed a slightly decreasing trend in hardness by prolong aging treatment. Tafel, electrochemical impedance spectroscopy (EIS), and cyclic polarization (CP) results showed that by aging treatment, corrosion rate and pitting corrosion increased, while exhibiting cold workability up to 20% reduction in thickness without cracking.