Effect of pre-compression deformation on aging precipitation behavior and mechanical properties of Mg–5Sn alloy

The study aimed to investigate the impact of different aging time and the compression prior to aging on the precipitation behavior and mechanical properties of the Mg–5Sn(wt.%) alloy. The findings revealed that compression prior to aging significantly reduced the time required to reach peak aging and resulted in a higher peak hardness, reaching up to 63 H V after 5 h of aging. The pre-compression introduced dislocation densities of up to 1.916 × 1015/m2, creating more nucleation sites for precipitated phases. As a result, pre-compression aging led to an order of magnitude more precipitated phases compared to direct aging. Interestingly, the study also discovered that hardness and strength did not exhibit a traditional positive correlation. The maximum strength was not achieved when hardness reached its peak. The increased numbers of precipitated phases were closely associated with an increase in strength but did not always enhance the corresponding hardness. The deviation of the hardness along with the increased precipitated phases was mainly imputed to the softening of the precipitated phases themselves. These findings highlight the complex relationship between hardness, strength, and the microstructures of the Mg–5Sn alloy during pre-compression and aging treatment.