Microstructures and Mechanical Properties of Mg–xAl–1Sn–0.3Mn (x = 1, 3, 5) Alloy Sheets

Abstract

The influence of Al alloying on the microstructures and the mechanical properties of Mg–xAl–1Sn–0.3Mn alloy sheets was investigated. The microstructure of Mg–xAl–1Sn–0.3Mn consisted of α-Mg and Mg17Al12 precipitates. Alloying with Al increased the amount of Mg17Al12 and the average grain size. Uniaxial tensile tests were carried out along the extrusion direction (ED), the transverse direction (TD) and 45° toward the ED. Mg–5Al–1Sn–0.3Mn alloy sheet exhibited the best combination of mechanical properties along the ED: a yield strength of 142 MPa, an ultimate tensile strength of 282 MPa and an elongation of 23%. The good performance of Mg–5Al–1Sn–0.3Mn sheet was mainly attributed to the large quantity of Mg17Al12 precipitates and a weak basal texture. Annealing caused static dynamic recrystallization, refined the grain size and enhanced the mechanical properties: yield strength of 186 MPa, ultimate tensile strength of 304 MPa, elongation of 21% along ED. Both strength and ductility were enhanced by Al alloying.