Effects of Ti content on microstructure and mechanical properties of as-cast AM60 magnesium alloy

As-cast microstructure of AM60 magnesium alloy with different Ti content was observed by OM (optical microscope), XRD(X-ray diffraction meter) and SEM (scanning electron microscope) and ambient tensile strength of the alloy was measured. The results reveal that the minor Ti addition can remarkably refine the as-cast microstructure of AM60 magnesium alloy. The desirable refinement effect with uniformly distributed fine second phase can be observed with 0.2%Ti addition, in which the semi-continuous β-Mg ₁₇Al ₁₂ distributed along grain boundary was converted into particle and dispersively distributed TiAl ₃ particle can be created in α-Mg phase, obtaining the highest tensile strength and elongation. When Ti addition is more than 0.2%, the tensile strength and elongation of the alloy are decreased with increasing in Ti addition as a result of the coarsenization of β-Mg ₁₇Al ₁₂ and α-Mg phase, and are superior to those of AM60 magnesium without Ti. The improvement of mechanical properties of AM60 magnesium alloy is attributed to Ti addition refining grain size and β-Mg ₁₇Al ₁₂ phase in the alloy as well as formed TiAl ₃ phase distributed into the matrix and secondary phase to strengthen the alloy.