Effects of Sn on Elevated-temperature Mechanical Properties of As-aged ZM61 Alloy

The elevated temperature mechanical properties and fracture mechanisms of as-aged ZM61-<i>x</i>Sn(<i>x</i>=0,6,8,10, mass fraction/%)alloys are investigated by optical microscope(OM), X-ray diffraction(XRD), scanning electron microscope(SEM) and high temperature tensile test. The results show that the phase compositions of ZM61-<i>x</i>Sn(<i>x</i>=6,8,10)alloys are α-Mg,α-Mn,MgZn₂ and Mg₂Sn phases. The Sn element can refine the microstructure, improve the high temperature tensile strength, but deteriorate the elongation of ZM61 alloy. The ultimate tensile strength of ZM61-<i>x</i>Sn(<i>x</i>=6,8,10) alloys with tensile test at 300℃ are 149,140, 145MPa, compared with ZM61 alloy which is carried out tensile test at the same temperature, the tensile strength increased 26%,17% and 23%, respectively. The elongation of ZM61-<i>x</i>Sn(<i>x</i>=0,6,8,10)alloys with tensile test at 300℃ are 39.95%,5.65%,7.01% and 6.33%. The tensile temperature exerts dominating effect for ZM61-<i>x</i>Sn(<i>x</i>=6,8,10)alloys on the fracture mechanism. As tensile temperature lower than 220℃, the alloys show transgranular fracture characteristics. The alloys show intergranular fracture characteristics when the tensile temperature is higher than 220℃