Molecular dynamics simulation of hydrostatic pressure effects on nucleation and grain growth in Al-7Si alloy

WJ Fan and SM Jiang and YL Wang and XH Chen and ZD Wang, MATERIALS TODAY COMMUNICATIONS, 46, 112675 (2025).

DOI: 10.1016/j.mtcomm.2025.112675

Molecular dynamics (MD) simulations were employed to investigate the effects of hydrostatic pressure on nucleation and grain growth in Al-7Si alloy during isothermal solidification. The mean first-passage time (MFPT) method was used to calculate the nucleation rate and critical nucleus size under varying hydrostatic pressures. The growth exponent was determined to assess the grain growth rate. The Johnson-Mehl-Avrami (JMA) method was applied to calculate the Avrami exponent, and the grain size after solidification was statistically analyzed. Uniaxial tensile simulations were performed to evaluate the mechanical properties of the Al-7Si alloy post-solidification. The results show that as hydrostatic pressure increases during solidification, the nucleation rate rises, while the critical nucleus radius remains nearly constant. Increased pressure slows the grain growth rate, inhibits grain growth, reduces the average grain size after solidification, and improves the overall mechanical properties of the Al-7Si alloy. These findings have significant scientific and engineering implications for Al-7Si alloys, providing valuable insights into the role of hydrostatic pressure in refining microstructures and enhancing material properties for various industrial applications.

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