Enhanced Mechanical Properties of ECAPed Mg-9Al-1Si Alloy by a Two-Stage Pretreatment
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A two-stage pretreatment (TSP), namely ultrasonic vibration treatment and solid-solution treatment, is proposed to improve the microstructure and properties of Mg-9Al-1Si alloy before equal-channel angular pressing (ECAP). The ultrasonic vibration treatment could distribute Mg2Si and Mg17Al12 phases uniformly in the alloy, while alloys subjected to solid-solution treatment exhibited a reduction in the amount of Mg17Al12 phase and improved plastic deformation capacity. In addition, the microstructure can be significantly refined, and broken Mg2Si phase and fine Mg17Al12 precipitates can reduce the average grain size during the ECAP process. Therefore, the strength and elongation of the ECAPed Mg-9Al-1Si alloy were improved simultaneously by introducing the TSP. The yield strength, ultimate tensile strength, and elongation of the ECAPed alloy with TSP were significantly enhanced to 290 MPa, 350 MPa, and 14.77%, respectively.
The authors gratefully acknowledge financial support from the Natural Science Foundation of Shanxi Province (201701D121045), National Natural Science Foundation of China (51301118, 51404166), and Shanxi Province Scientific Facilities and Instruments Shared Service Platform (201805D141005).