Effect of lamellar LPSO phase on mechanical properties and damping capacity in cast magnesium alloys

Abstract

The effect of the lamellar long period stacking order (LPSO) phase on both mechanical properties and damping capacity of magnesium alloys is still vague. After heat treatment at 540 °C for 4 h and 450 °C for 10 h, the Mg-10Gd-2Y–1Zn-0.5Zr-0.2Nd (wt%) alloy with the lamellar LPSO phase is prepared to study the influence of lamellar LPSO phase on damping capacity and mechanical properties. Combined transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipped with electron back-scattering patterns (EBSD) system, it is surprisingly found that the growth direction of the lamellar LPSO phase on basal plane is nearly parallel to the slip direction of basal dislocations, which is benefit from dislocations movement on basal plane. The dislocations move on basal plane easily, lead to a relative high damping capacity. The alloy with LPSO phases shows higher ultimate tensile strength (UTS) and elongation (EL), increased from 234 MPa to 2.6% to 254 MPa and 4.6%, respectively. The lamellar LPSO phase has an attribution to UTS and EL due to its kink deformation mechanism. Therefore, the lamellar LPSO phase can be used as a functional phase to enhance the damping capacity and mechanical properties at the same time, and providing new ideas about preparing high-strength and high-damping magnesium alloy.