Dependence of phase selection on cooling rates in as-cast Al-Si-Mg alloys
(1.陕西省西安市西北工业大学材料科学与工程学院
2.Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
3.College of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China)
2.Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
3.College of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China)
Abstract: The effect of cooling rate on the solidification process of Al-2.06%Si-1.58%Mg was numerically and experimentally investigated. The solidification paths and the phase precipitation sequence were predicted based on the solute transportation analysis in the solidification process by coupling the thermodynamic calculation. Due to the different solute diffusion speeds, the solidification paths can be largely influenced by the cooling rates. Different phase precipitation sequences can be obtained through calculation under different cooling rates. And the later experiments have also proved this phenomenon. In the researched Al-2.06%Si-1.58%Mg alloy, the solidification sequences are α(Al)→α(Al)+Si→α(Al)+Mg2Si+Si under low cooling rate and α(Al)→α(Al)+Mg2Si→α(Al)+Mg2Si+Si under high cooling rate, respectively. The experimental results confirm the calculation predications.
Key words: Al-Si-Mg alloys; cooling rate; solute transportation; phase selection