Improvement in as-cast strength of high pressure die-cast Al-Si-Cu-Mg alloys by synergistic effect of Q-Al5Cu2Mg8Si6 and θ-Al2Cu phases

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:802

Article

Zhu, Xiangzhen¹  Dong, Xixi¹  Blake, Paul²  Ji, Shouxun¹ 

[1] Brunel Univ London, Brunel Ctr Adv Solidificat Technol BCAST, Uxbridge UB8 3PH, Middx, England

[2] Jaguar Land Rover, Ctr Engn, Abbey Rd, Coventry CV34 4LF, W Midlands, England

关键词: Aluminium alloys;    Microstructure;    Mechanical properties;    Strengthening mechanism;    Precipitate strengthening;    Synergistic effect;   

DOI  :  10.1016/j.msea.2020.140612

来源: Elsevier

【 摘 要 】

A novel high-strength die-cast Al-Si-Cu-Mg alloy has been developed in the present work. Experimental results indicated that the combination of different amounts of theta-Al2Cu and Q-Al5Cu2Mg8Si6 phases could provide a same yield strength but different elongations due to the differences in size and distribution of these two phases. By optimizing the synergistic strengthening of Q-Al5Cu2Mg8Si6 and theta-Al2Cu phases, the balanced strength-ductility trade-off was achieved at 3.0 wt% Cu and 0.9 wt% Mg, offering a yield strength of 225 MPa and an elongation of 4.3% under as-cast condition. Except the normal Q and theta large lamellar or blocks located in alpha-Al grain boundary, numerous nanoscale Q-Al5Cu2Mg8Si6 precipitates (mostly under 200 nm) were also observed inside the alpha-Al grains in the newly developed alloy. Thermodynamic calculation was performed using Pandat 2018 software to explain the formation and distribution of strengthening phases. It was found that Q-Al5Cu2Mg8Si6 can be precipitated from (1) the melt directly via liquid-solid reaction and (2) alpha-Al phase via solid-solid reaction. The nanoscale Q-Al5Cu2Mg8Si6 particles are considered to be precipitated via the latter solid reactions.

【 授权许可】

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