Effect of Mg₂Sn Particles on Microstructure and Mechanical Properties of aged AZ Series Magnesium alloy.

Magnesium alloys have received a considerable research focus in transportation sector due to its lightness and environmental legislation to reduce green-house effects. In this work, a magnesium alloy containing aluminium, zinc and tin as major alloying addition was studied. After casting, the alloy was homogenised and hot-rolled at 400 °C. This temperature was sufficient to promote extensive dynamic recrystallization as evident from microstructure. Texture was obtained as pole figures. The pole figures clearly revealed basal texture which also ensures the rotating of the crystals along the rolling directions. Aging of the alloy was conducted up to 30 hr at 170 °C. Surprisingly, this T5 treatment showed increased mechanical properties with time. This behaviour was studied in scanning electron microscopy. It was found that spherical-shaped Mg₂Sn particles were precipitated as both nano-size particles and micron-size particles. These particles were responsible to age-strengthening of the alloy. Since particle stimulated nucleation is size dependent phenomenon, only Mg₁₇Al₁₂ phase effectively participated in grain refining. Aging response was entirely due to the presence and coarsening of Mg₂Sn particles.