Low-Temperature Mechanical Properties and Constitutive Model of TiZrHfNbX (X=Ta, Cu, Al) High-Entropy Alloy

In order to investigate the effects of different elements on the low-temperature mechanical properties of TiZrHfNb high-entropy alloys, mechanical tests of TiZrHfNbX (X=Ta, Cu, Al) under the coupling temperat ure (213～293 K) and strain rate (0.000 1～2 000 s−1) were conducted using universal testing machine and Hopkinson pressure bar experimental system. The relationship between phase composition, microstructure, and static/dynamic mechanical response of the materials was investigated using various characterization meth ods. The results show that the morphology and distribution of the second phase result in discrepancies in the cryogenic mechanical properties of the three high-entropy alloys. In addition, the low temperature induces high er resistance to dislocation motion, causing the material to exhibit significant low-temperature strengthening ef fects. Finally, the modified Johnson-Cook (J-C) constitutive model is proposed for the strain rate strengthening term and the temperature term to describe the mechanical behavior of TiZrHfNbX (X = Ta, Cu, Al) at low temperatures.