Microstructure and mechanical properties of AZ31 magnesium alloy reinforced with novel sub-micron vanadium particles by powder metallurgy

In this study, a novel fine-grained AZ31 magnesium (Mg) alloy reinforced with sub-micron vanadium particles (V-P) was prepared by powder metallurgy (P/M). It was found that V-P could accelerate the pile-up of dislocations and the refinement of Mg crystallite sizes during the milling process. The Mg matrix was refined to nanocrystalline scale after milling for 90 h, and the ultimate average crystallite size was only 25 nm. Meanwhile, a homo-geneous distribution of the sub-micron V-P in Mg matrix was achieved. After hot-extrusion process, the average grain size of Mg matrix was 3.08 mm, which reached fine-grained scale. Additionally, the AZ31-2.5 wt % V-P composite exhibited competitive mechanical properties. Compared to the as-cast AZ31 Mg alloy, the microhardness, yield strength, ultimate tensile strength and elongation of AZ31-2.5 wt % V-P composite increased by 102%, 128%, 59% and 10%, respectively. The grain boundary strengthening played a dominant role in improve-ment of strength. Simultaneously, the strengthening mechanisms of thermal mismatch, Orowan strengthening and load transfer also made a contribution. Besides that, the fracture mechanism of the AZ31-2.5 wt % V-P composite included ductile and brittle fracture mode. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

In this study, a novel fine-grained AZ31 magnesium (Mg) alloy reinforced with sub-micron vanadium particles (V-P) was successfully prepared by powder metallurgy. The composite exhibited competitive mechanical properties with improved microhardness, yield strength, ultimate tensile strength, and elongation. The strengthening mechanisms of grain boundary strengthening, thermal mismatch, Orowan strengthening, and load transfer contributed to the improvement of strength, while the fracture mechanism included both ductile and brittle modes.