Addressing the strength-ductility trade-off in a cast Al-Li-Cu alloy-Synergistic effect of Sc-alloying and optimized artificial ageing scheme

• 作者: Jinshuo Zhang Guohua Wu Liang Zhang Xiaolong Zhang Chunchang Shi Xin Tong
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2022,（1）
• 页码范围: 212-225
• 页数: 14页
• 语种: 英文

摘要

A dramatic improvement of strength and ductility of cast Al-2.SLi-1.5Cu-1Zn-0.5Mg-0.15 Zr alloy was obtained by the collaboration of Sc-alloying and optimized ageing scheme.Joint and independent influ-ence of Sc-alloying and different ageing temperatures were investigated.The results revealed that a substantial increase was realized in the hardness of Sc-containing alloy,and the ageing response time was only influenced by ageing temperature.Coarse and heterogeneous δ'(Al3Li),wide δ'-precipitation free zones (δ'-PFZs),and a large amount of T1 (Al2CuLi) precipitates were observed in Sc-containing alloy aged at 175 ℃,which resulted in superior yield strength and poor elongation.The Sc-containing alloy obtained an excellent combination of ductility (elongation =8.2 ％) and tensile strength (ultimate strength=565 MPa) suffered to 150 ℃ ageing for 64 h.The increase in the elongation was mainly due to the com-bined effect of grain refining,much finer δ',and extremely narrow δ'-PFZs (＜10 nim),while the higher strength was mainly attributed to the formation of Al3(Sc,Zr,Li) composite particles and a large amount of S'(Al2CuMg) phase.However,the enhancement of the different ageing temperature (150 ℃ and 175℃) on the mechanical properties of the alloys without Sc addition was not obvious.