Microstructural characteristics and mechanical properties of cast Al-3Li-xCu-0.2Zr alloy

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• 作者：Antao Chen ; Guohua Wu ; ^{ghwu@sjtu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Liang Zhang ; ^{liangzhang08@sjtu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Xiaolong Zhang ; Chunchang Shi ; Yanlei Li
• 关键词：Microstructure ; Cu addition ; δ&prime ; particles ; Precipitation-free zones ; Mechanical property
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：20 November 2016
• 年：2016
• 卷：677
• 期：Complete
• 页码：29-40
• 全文大小：9812 K

文摘

The microstructures and mechanical properties of cast Al-3Li-xCu-0.2Zr alloy were investigated. The results showed that Cu addition could slightly refine the grain size of as-cast alloy. Cu element was significantly enriched at the grain boundaries, and Cu-rich intermetallic compounds were formed in the Cu-containing alloys during casting. The peak hardness increased and the time to peak ageing decreased with the increase of Cu content. Cu addition also had a pronounced influence on the precipitation behavior of Al-3Li-xCu-0.2Zr alloys, i.e. the number density, size and distribution of T₁-Al₂CuLi and θ′-Al₂Cu phases. The tensile strength was effectively improved after 2 wt% Cu addition compared with Al-3Li-0.2Zr alloy. A good combination of strength to ductility could be obtained in Al-3Li-2Cu-0.2Zr alloy after solution and ageing 32 h at 175 °C. The precipitation-free zones (PFZs) were developed with the coarsening of δ′-Al₃Li particles in the peak-aged (PA) and over-aged (OA) state, promoting the poor ductility and premature failure.