Effect of Cd micro-addition on microstructure and mechanical properties in ternary Al-Si-Cu alloy

• Published in: Journal of alloys and compounds Vol. 851; p. 156739
• Main Authors: Cao, Yudong, Chen, Xiaohua, Wang, Zidong, Chen, Kaixuan, Tang, Weizhong, Pan, Shiwei, Yang, Xinghai, Qin, Junwei, Li, Shaohua, Wang, Yanlin
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.01.2021; Elsevier BV
• Subjects: Al alloy; Alloys; Aluminum base alloys; Copper; Copper base alloys; Mechanical properties; Micro-alloying; Microstructure; Nucleation; Precipitates; Precipitation; Silicon; Strengthening; Thermodynamic calculation; Yield strength; Yield stress; Micro-alloying; Mechanical properties; Precipitation; Al alloy; Thermodynamic calculation
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.156739

In present work, Al-7Si-4Cu alloys with/without 0.28 wt % Cd addition were fabricated. Both alloys were solution treated at 500 °C for 10 h, followed by quenching and subsequently ageing at 165 °C for different times of 0.5–20 h. Results showed that hardness, strength and ductility at peak-aged state for Cd-doped alloy were simultaneously enhanced by comparing with Cd-free alloy. Quantitative analysis results of microstructure indicated that with Cd addition a finer and denser microstructure of θ′ can be obtained. Based on microstructure characterization as well as thermodynamics and kinetics calculations, the mechanism for obtaining a finer and denser θ′ was discussed, which was considered as a result of the pre-precipitation and heterogeneous nucleation effect of Cd-rich particles. Improved mechanical properties for Cd-doped alloy were discussed to be ascribed to the precipitation of larger number density and less size of θ′. The increase of yield strength with Cd was quantitatively described by the strengthening models. The results indicated that yield strength increment in alloy B was dominated by strengthening contribution of finer and denser θ′ precipitates. [Display omitted] •Al-Si-Cu-Cd alloy was fabricated with finer and denser θ′ by Cd addition.•Hardness, strength and ductility were enhanced simultaneously in the Cd-doped alloy.•Heterogeneous nucleation effect of Cd-rich particles on refining θ′ was found.•Strengthening and toughening mechanisms in the Cd-doped alloy were discussed.