Wang, Jun; Liu, Yixian; Jiao, Xiangyi; Xie, Honglan; Deng, Biao; Xiong, Shoumei

MATERIALS TODAY COMMUNICATIONS

2025, ,

Wang, Jun; Liu, Yixian; Jiao, Xiangyi; Xie, Honglan; Deng, Biao; Xiong, Shoumei

The synergistic effect of Cu content and cooling rate on the size and morphology difference of PSPs (primary silicon particles) in different Al-Si-Cu alloys were characterized using synchrotron X-ray tomography. With low cooling rate, the size of PSPs increased as the Si content increased regardless of the Cu addition. With high cooling rate, the average size of PSPs decreased from 60.1 mu m to 50.3 mu m in the 20 wt% Si alloys as the Cu content increased. High cooling rate amplified the effect of Cu content on growth of aluminum dendrites, eutectic microstructures and PSPs. Quantitative analysis of PSPs morphology demonstrated that an increase in Cu content enhanced the likelihood of local twinning occurrence, ultimately leading to the formation of chain-like morphologies. The combined effect of copper content and cooling rate predominantly influenced the growth of the microstructure by altering the local undercooling. This alteration was subsequently manifested as abnormal size and morphology of PSPs, providing critical insights into the microstructural evolution mechanisms of Al-Si-Cu alloys under different solidification conditions.