Simultaneous enhancement of strength and ductility for AZ31 magnesium alloy by pre-twinning induced heterostructure. (December 2022)

• Record Type: Journal Article
• Authors: Chen, Wenhuan; He, Weijun; Jiang, Bin; Pan, Fusheng
• Is Part Of: International journal of plasticity. Volume 159(2022)
• Publication Date: 2022-12
• Subjects: Twin -- Misorientation -- Heterogeneity -- Local strain -- Deformation mechanism; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2022.103483
• Languages: English
• ISSNs: 0749-6419

Abstract

Highlights: The strength and ductility of the AZ31 alloy are simultaneously enhanced after the introducing of a high fraction of twin-matrix pairs. Without significantly changing the global SFs, many more non-basal slip systems are activated in the AZ31 alloy due to the deformation compatibility requirements of the twin-matrix interaction. The uniformity of the strain distribution at the grain-size scale is enhanced as result of the extra activated non-basal slip. Abstract: Pre-twinning was used to tailor the strength and ductility of AZ31 magnesium alloy. Simultaneous enhancements in both ductility and strength were achieved in the AZ31 after the introducing of a high fraction of twin-matrix pairs. The slip trace analysis indicated that although the area-weighted average global Schmid factors (SFs) were not significantly changed, much more non-basal slip was activated in the pre-twinned sample compared with that in the as-received sample, which was beneficial to achieving higher work hardening and obtaining higher uniform elongation. The high-resolution digital image correlation (DIC) combined with ex-situ electron backscatter diffraction (EBSD) characterization revealed that the uniformity of the grain-size scale strain distribution was improved and the local strain concentration at the boundary was reduced during the loading as result of the extra activated non-basal slip, which delayed intergranular crack initiation and increased ductility. The activation of much non-basal slip with high critical resolved shear stress, the hetero-deformation, and the fine equivalent grain size caused the strengthening of the AZ31 sample with a high fraction of twin-matrix pair interfaces. These results imply that tailoring the twin-matrix interface density is an effective strategy to achieve excellent strength-ductility combinations in HCP metals.