A comparative investigation of shock response in high entropy Cantor alloys by MEAM and LJ type potentials

A Sircar and PK Patra, MATERIALS TODAY COMMUNICATIONS, 33, 104843 (2022).

DOI: 10.1016/j.mtcomm.2022.104843

We assess the effect of interatomic potential in determining the shock response of the high entropy Cantor alloy through large scale non- equilibrium molecular dynamics simulations. In literature, two different potentials have been suggested for modeling Cantor alloys at atomic scale - the 2NN MEAM potential, henceforth termed as the MEAM potential, and the Lennard-Jones (LJ) type-potential. We show that the MEAM potential results in a different shock response than the LJ type- potential - (i) the shock wave speed and the pressure behind the shock front are smaller for MEAM than the LJ type-potential, (ii) no twinning is observed with the MEAM potential along the 100 direction unlike that with the LJ type-potential, and (iii) the shock induced phase transition from FCC to HCP is observed along the 100 direction only with the LJ type-potential. Our numerical results with the LJ type- potential are in agreement with the experiments as well, where twinning and phase transition have been observed. Looking at the morphology of the post-shocked samples at different times, we identify the mechanism behind the phase transition. Lastly, we subject the post-shocked structure to uniaxial tensile tests to show that for the 111 direction, a greater fracture strain than the unshocked structure is obtained, suggesting a higher fracture toughness.

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