Effect of friction stir processing on microstructure and tensile properties of as-cast Mg–8Li–3Al–2Sn (wt.%) alloy. (May 2020)

• Record Type: Journal Article
• Authors: Chen, Xiaoyang; Zhang, Yang; Cong, Mengqi
• Is Part Of: Vacuum. Volume 175(2020)
• Publication Date: 2020-05
• Subjects: Mg–Li alloy -- Friction stir processing -- Microstructure -- Tensile properties; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2020.109292
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: A new Mg–8Li–3Al–2Sn (LAT832, wt.%) alloy was cast by vacuum induction melting and processed by friction stir processing (FSP). Microstructure and tensile properties of as-cast and FSP LAT832 samples were studied comparatively. It is found that, as-cast LAT832 sample consists of α-Mg+β-Li duplex-phase matrix and MgLiAl2 and Li2 MgSn intermetallic phases. After FSP, an inverted-trapezoidal stir zone (SZ) is formed and onion-ring structure occurs at the center of SZ. Complete dynamic recrystallization (DRX) occurs in SZ of FSP LAT832 sample and α-Mg grains are significantly refined, but the microstructure is inhomogeneous. Li2 MgSn phase is crushed into coarse particles while MgLiAl2 phase is decomposed into fine AlLi particles. Tensile properties of as-cast LAT832 sample are significantly enhanced by FSP, which benefits from strengthening effect of grain refinement of α-Mg phase and broken Li2 MgSn particles. Highlights: Onion-ring structure occurs at the center of stir zone. Dynamic recrystallization occurs in stir zone of friction stir processing sample. Li2 MgSn phase is crushed into coarse particles during friction stir processing. MgLiAl2 phase is decomposed into fine AlLi particles during friction stir processing. The tensile properties are significantly enhanced by friction stir processing.