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).
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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