Strengthening Effect of Extruded Mg-8Sn-2Zn-2Al Alloy: Influence of Micro and Nano-Size Mg₂Sn Precipitates

• Published in: Materials Vol. 10; no. 7; p. 822
• Main Authors: Cheng, Weili, Bai, Yang, Wang, Lifei, Wang, Hongxia, Bian, Liping, Yu, Hui
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI 18.07.2017; MDPI AG
• Subjects: extrusion; Mg-Sn alloy; microstructure; precipitation; strengthening; Mg-Sn alloy; precipitation; strengthening; microstructure; extrusion
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma10070822

In this study, Mg-8Sn-2Zn-2Al (TZA822) alloys with varying Mg₂Sn contents prior to extrusion were obtained by different pre-treatments (without and with T4), and the strengthening response related to micro and nano-size Mg₂Sn precipitates in the extruded TZA822 alloys was reported. The results showed that the morphology of nano-size Mg₂Sn precipitates exhibits a significant change in basal plane from rod-like to spherical, owing to the decrement in the fraction of micro-size particles before extrusion. Meanwhile, the spherical Mg₂Sn precipitates provided a much stronger strengthening effect than did the rod-like ones, which was ascribed to uniform dispersion and refinement of spherical precipitates to effectively hinder basal dislocation slip. As a consequence, the extruded TZA822 alloy with T4 showed a higher tensile yield strength (TYS) of 245 MPa, ultimate tensile strength (UTS) of 320 MPa and elongation (EL) of 26.5%, as well as a lower degree of yield asymmetry than their counterpart without T4. Detailed reasons for the strengthening effect were given and analyzed.