Study on the microstructure and mechanical properties of Mg–Al–Li–Zn–Ti multi-component alloy

Abstract

A novel magnesium-based multi-principal element alloy with the chemical formula Mg54Al22Li11Zn11Ti2 was prepared using the vacuum induction melting method and subsequently extruded at 350 °C. The phase composition of the alloy in its as-cast state and the microstructural changes after extrusion were investigated using various analytical techniques, including SEM, EBSD, EPMA, and TEM. The presented outcomes showed that the as-cast alloy exhibited lattice distortion and fine grain with segregation, while the average grain size decreased significantly and the second phase became more dispersed after extrusion. The mechanical properties of both the as-cast and extruded alloys, including microhardness, tensile strength, compressive strength, and wear characteristics, were evaluated. The extruded alloy demonstrated significant improvements in mechanical properties compared to the as-cast alloy, with a compressive strength of up to 460 MPa, which can be attributed to both fine grain and precipitation strengthening. Both the as-cast and extruded alloys exhibited high hardness due to the accumulation of local dislocations caused by the interlaced precipitation of sub-grains during the super-solid solution state in the as-cast condition. The hardness enhancement in the extruded state resulted from grain refinement induced by DRX. Furthermore, wear tests revealed that the extruded alloy, characterized by smaller second phase sizes, exhibited excellent wear resistance, with wear failure occurring in the form of abrasive and oxidative wear in both the cast and extruded alloys.

Keywords

• Magnesium-based multi-component alloys
• Hot extrusion
• Microstructure
• Wear performance