Molecular dynamics study of the effect of heat treatment on residual stress and microdefect in SiCp/Al

Y Shi and YN Xiong and Q Zhang and XB Li and CC Yin and JZ He and X Luo and J Wang, MATERIALS TODAY COMMUNICATIONS, 45, 112332 (2025).

DOI: 10.1016/j.mtcomm.2025.112332

Understanding the mechanisms behind the evolution of microstructure and residual stress during heat treatment is crucial for improving the properties of metal matrix composites (MMCs). This study employs the molecular dynamics (MD) method to conduct six distinct cyclic heat treatments on SiCp/Al composites. The synergistic mechanisms of local residual stresses and microscopic defects during different heat treatments were explored. We found that all heat treatments successfully alleviate residual stresses in the first few cycles, with the gradual cooling strategy being the most effective after the second cycle. The dimensions of SiCp/Al composites consistently reduce after each cycle with high-temperature treatment, however in the later cycles stress accumulation and microstructural transformation occur. In the cycles with cryogenic (liquid nitrogen temperature) treatment, a localized stress concentration occurs after a certain number of cycles and leads to periodic dislocation avalanches, as well as a dramatic increase in the dimension. After cyclic heat treatment, both the number and size of stacking faults increase, the dislocation type may undergo a transformation. The study provides atomistic insights into understanding the thermal stress and microstructural evolution in SiCp/Al during heat treatment.

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