摘要
In this study, the precipitation transformation and age hardening of solution-treated Mg-9Gd-4Y-2Zn-0.5Zr(wt.%) alloy were investigated at different aging treatment parameters. The precipitation sequences of the alloy aged at 200℃, 250℃ and 300℃ are β’’(DO19) → β’(BCO) → β(FCC), β’’(DO19) → β’(BCO) → β_(1)(FCC) → β(FCC) and β(FCC), respectively. The streaks sequences of the alloy aged at 200℃, 250℃ and 300℃ are SF, SF → 14H-LPSO and SF → 14H-LPSO, respectively. For the alloy aged at 200℃ and 250℃, the increase in hardness with increasing aging time is contributed from the increase in precipitate volume fraction and the transformation from β’’ to β’ phase with basal → prismatic and spherical → spindle-like precipitate changes. The decrease in hardness after the peak-aging stage is attributed to the appearance of micro-sized β precipitates. Because of the smaller size of precipitates and the triangular arrangement of β’ precipitate, the hardness of the alloy aged at 200℃ is higher than that aged at 250℃. For the alloy aged at 300℃, the appearance of only micro-sized β precipitate and its coarsening with increasing aging time leads to the lowest hardness and an overall decrease in hardness with the aging time.
基金
financially supported by the Key R&D program of Shanxi Province (International Cooperation) (No.201903D421036)
the Natural Science Foundation of Shanxi Province (No.201901D111176)
the Joint Funds of the National Natural Science Foundation of China (Grant No.U20A20230)
the Bureau of Science,Technology and Industry for National Defense of China (No.WDZC2019JJ006)
the National Natural Science Foundation of China (Grant No.52075501)
Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (No.201802072)
the National Defense Basic Scientific Research Program (No.JCKY2018408B003)
the XX Supporting Scientific Research Project (No.xxxx-2019-021)。
