Improvement in the age-hardening response of Mg-7Sn alloy by compressive stress-assisted aging

Stress aging is an effective method to improve age-hardening behavior of Mg alloys. In this paper, the stress aging was applied to improve poor age-hardening response of Mg-7Sn alloy. The age-hardening behavior, microstructure evolution and mechanical properties of Mg-7Sn alloy with an external compressive stress were investigated. The stress aging significantly altered the size, morphology, amounts and distribution of Mg2Sn phase. During the stress aging, micro/nano scale Mg2Sn particles precipitated on the basal plane of the stress aged alloy and their volume fraction remarkably increased as compared with the isothermal aging alloy. Interestingly, small amounts of Mg2Sn phases precipitated on the non-basal planes. The stress aging significantly reduced the peak aging time (96 h) and increased peak aging hardness (68.4 HV). The tensile tests showed that the stress peak -aged alloy at 80 MPa exhibited the highest tensile strengths (s0.2 1/4 140 MPa and sb-1/4 217 MPa), which were mainly attributed to the precipitation strengthening of Mg2Sn phase.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).