Molecular dynamics simulations of the effect of gradient grain size on the mechanical properties of polycrystalline titanium

Y Niu and YJ Jia and X Lv and YC Zhu and YQ Wang, MATERIALS TODAY COMMUNICATIONS, 45, 112457 (2025).

DOI: 10.1016/j.mtcomm.2025.112457

In this study, the effect of different grain size gradients on the deformation mechanism of polycrystalline titanium was investigated using molecular dynamics simulations. The simulations were conducted at a temperature of 300 K, with a strain rate of 5 x 10(8) s(-1), under tensile loading conditions. The results indicate that the peak stress increases with the grain gradient, and the elasticity modulus also shows a positive correlation with the grain gradient. The material structures remain stable up until the peak stress is reached. After the peak stress, the HCP structure decreases initially and then increases, while the other structures first increase and then decrease. The BCC and FCC structures initially increase and gradually stabilize. As the grain gradient increases, the transformation from the HCP structure is reduced. During the deformation process, the dislocation density initially decreases and then increases, with the lowest dislocation density occurring at the peak stress. The dislocation density increases with the grain gradient. In models with low grain gradient values, the grain boundaries generally remain relatively flat, whereas in models with higher grain gradients, the grain boundaries are more susceptible to deformation.

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