Microstructure and mechanical properties of AZ91/TiP magnesium matrix composite ribbons fabricated by melt-spinning

There are few studies on the preparation of magnesium matrix composites (MMCs) by rapid solidification. This study aims to add minor amounts of Ti particles to AZ91 alloy and prepare AZ91/Ti_P MMC ribbon by Melt-Spinning (MS). The effects of Ti particle content on the microstructure and mechanical properties of AZ91/Ti_P ribbon were studied by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), transmission electron microscopy (TEM), three-dimensional profiling (3D-P) and calculation of supercooling rate. The results show that the grain refinement of AZ91 ribbon prepared by rapid solidification is very significant and the grain refinement is further improved with the increase of Ti particle content; at the same time, the growth of β-Mg₁₇Al₁₂ is inhibited, and the interface reaction between Ti and Mg leads to the formation of interfaces around Ti particles. These nano-scale Ti₃Al and Al₃Ti interface compounds uniformly wrap the Ti particles. It is believed that the addition of Ti particles not only helps to refine the surrounding grains, but also increases the dislocations in the MMC ribbon and forms a good interface, thereby improving the mechanical properties. Compared with AZ91 alloy ribbon, the yield strength and tensile strength of MMC material containing 5 wt.% Ti particles increased by 25.0 % and 22.7 % respectively. The elongation only decreased by 10.9 %. AZ91/5 wt.% Ti_P ribbon has a better balance between high strength and high elongation. The analysis shows that the strengthening effect of this mechanical property is mainly attributed to fine grain strengthening, dislocation strengthening and non-basal slip.