Effect of Pre-Ageing on the Precipitation Behaviors and Mechanical Properties of Al-7Si-Mg Alloys  

作　　者：Wen-Chi Chen Sheng-Lon Lee An-Hung Tan 

机构地区：[1]Department of Mechanical Engineering, National Central University, Taiwan [2]Department of Mechanical Engineering, Chien Hsin University, Taiwan

出　　处：《Journal of Materials Science and Chemical Engineering》2018年第3期55-67,共13页材料科学与化学工程（英文）

摘　　要：For alloys that are quenched to 25℃ room temperature, there are Mg-Mg, Si-Si and Mg-Si clusters shown by exothermic peaks in a A357 alloy. However, there are no clear Mg-Mg, Si-Si and Mg-Si cluster exothermic peaks in a A356 alloy. Hence, the low Mg content in a A356 alloy has less impact with natural ageing. The natural ageing impact on the mechanical properties of a A357 alloy is higher than a A356 alloy due to the precipitation of Mg-Si clusters for which the nucleation size does not reach the critical size. The 90℃ pre-ageing process could promote Mg-Si clusters to a critical size to become the nucleation site for of β''. This then increases the artificial ageing strength and mitigates the impact of natural ageing.For alloys that are quenched to 25℃ room temperature, there are Mg-Mg, Si-Si and Mg-Si clusters shown by exothermic peaks in a A357 alloy. However, there are no clear Mg-Mg, Si-Si and Mg-Si cluster exothermic peaks in a A356 alloy. Hence, the low Mg content in a A356 alloy has less impact with natural ageing. The natural ageing impact on the mechanical properties of a A357 alloy is higher than a A356 alloy due to the precipitation of Mg-Si clusters for which the nucleation size does not reach the critical size. The 90℃ pre-ageing process could promote Mg-Si clusters to a critical size to become the nucleation site for of β''. This then increases the artificial ageing strength and mitigates the impact of natural ageing.

关 键 词：Pre-Ageing PRECIPITATION MECHANICAL Property Al-7Si-Mg Alloys 

分 类 号：TG14[一般工业技术—材料科学与工程]