Effect of forced-air cooling on the microstructure and age-hardening response of extruded Mg-Gd-Y-Zn-Zr alloy full with LPSO lamella. (20th May 2021)

• Record Type: Journal Article
• Authors: Wu, S.Z.; Nakata, T.; Tang, G.Z.; Xu, C.; Wang, X.J.; Li, X.W.; Qiao, X.G.; Zheng, M.Y.; Geng, L.; Kamado, S.; Fan, G.H.
• Is Part Of: Journal of materials science & technology. Volume 73(2021)
• Page Start: 66
• Page End: 75
• Publication Date: 2021-05-20
• Subjects: Mg-RE alloy -- LPSO phase -- Dynamic recrystallization -- Precipitation -- Mechanical properties; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2020.09.020
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: Forced-air cooling hinders DRX and causes smaller DRXed grain, stronger basal texture and higher dislocation density. Forced-air cooling promotes dynamic precipitation and γ′ phases then slightly restricts the precipitation of β′ phases. The extruded alloy with forced-air cooling after peak-ageing shows TYS of 439 MPa and elongation to failure of 18.6 %. Abstract: The homogenized Mg-8.2Gd-3.8Y-1.0Zn-0.4 Zr (wt.%) alloy full of plate-shaped long period stacking ordered (LPSO) phases was hot extruded in the atmosphere and cooled by the forced-air, then the effect of forced-air cooling on the microstructure and age-hardening response of the alloy was investigated in this work. The results show that in comparison with the extruded sample cooling in the atmosphere, the forced-air cooling restricts dynamic recrystallization (DRX) and brings about finer dynamic recrystallized (DRXed) grain size, stronger basal texture and higher dislocation density. Furthermore, the forced-air cooling promotes the dynamic precipitation in the DRXed regions and facilitates formation of plate-shaped LPSO phases and γ′ phases with smaller interspacing in the unrecrystallized (unDRXed) regions, then slightly restricts the precipitation of β′ phases during aging. After peak-ageing treatment, the extruded sample with forced-air cooling shows superior tensile properties with a tensile yield strength of 439 MPa, an ultimate tensile strength of 493 MPa, and elongation to failure of 18.6 %.