Maintaining High Strength at High Temperature in a Mg-Y-Zn-Gd Alloy by Heat Treatments and Severe Deformation Processing

The evolution of mechanical properties between room temperature and 573 K (300 degrees C) has been studied in a Mg-Y-Zn-Gd alloy under different heat treated and thermomechanically processed conditions. The different distributions of long period stacking ordered phase and precipitation of lamellar Gd-rich phase, modified by severe deformation processing, lead to strengths ranging between 112 and 175 MPa at 573 K (300 degrees C). Microstructures have been evaluated under different processing conditions and comparison made with a similar alloy without Gd previously studied. Although the alloys can achieve similar room temperature strengths, only the Gd-containing alloy can retain sufficient high strength at temperatures above 473 K (200 degrees C). This is due to the strengthening effect of the lamellar Gd-rich precipitates that are broken and redistributed during the severe deformation processing. (C) The Minerals, Metals & Materials Society and ASM International 2015