Effects of Sn on microstructure and tensile properties in a binary Mg-1Ca alloy

Abstract

The evolution of microstructure and tensile properties of a binary Mg-1Ca alloy with different tin additions (1, 2, and 4 wt%) was investigated under various conditions of temperatures and strain rates. Mg-1Ca, Mg-1Ca-1Sn, Mg-1Ca-2Sn, and Mg-1Ca-4Sn samples were cast and homogenized. The homogenized samples were rolled at 400 °C. Optical microstructures of both cast and rolled samples were taken for microstructural analysis. Scanning electron microscopy of four rolled samples was carried out to identify the phases present. Tensile test of rolled alloys was carried out at temperatures 300, 350, 400, and 450 °C, and at two different strain rates 5x ${10}^{-4}$ $s^{-1}$ and 1x ${10}^{-4}$ $s^{-1}$. It was found that tin addition increased dendrite formation in as-cast alloys and continuously reduced the grain sizes of rolled alloys. The addition of a small amount of Sn increased both strength and elongation to failure values. However, a higher amount of Sn addition lowered the properties to some extent due to the formation of excessive intermetallic particles. At lower temperatures, higher strength and lower elongation to failure values were found due to higher work hardening. Conversely, at elevated temperatures, strength values were reduced due to inevitable softening and greater grain growth.