Microstructure and properties of WE93 alloy
(1. State Key Laboratory of Nonferrous Metals and Processes,
Beijing General Research Institute for Nonferrous Metals, Beijing 100088, China;
2. Southwest Aluminum (Group) Co., Ltd, Chongqing 401326, China)
Beijing General Research Institute for Nonferrous Metals, Beijing 100088, China;
2. Southwest Aluminum (Group) Co., Ltd, Chongqing 401326, China)
Abstract: The microstructure of WE93 alloy in different states and the mechanical properties at room temperature were investigated, and the creep behavior of the extruded and aged alloy at 200 °C and at stress of 100, 125 and 150 MPa was also discussed. The result shows that the microstructure of as-cast WE93 alloy consists of α-Mg, Mg12(MM) and Mg24Y5 with an average grain size of 45 μm. After being homogenized at 535 °C for 18 h, the Mg24Y5 phase is dissolved completely and there is only Mg12(MM) phase left around the grain boundaries. The grains do not grow up as prolonging the homogenization time. The extruded alloy has better mechanical properties than the as-cast alloy, especially the elongation increases to 12.5%. The extruded and aged alloy exhibits the highest yield strength and ultimate tensile strength of 315 and 385 MPa, respectively, however, the elongation decreases to 6.5%. The extruded and aged alloy exhibits good creep resistance at 200 °C and at stress of 100−150 MPa. The creep stress exponent n is 2.97, suggesting that grain boundary sliding plays a dominant role at the corresponding temperature and applied stresses.
Key words: rare-earth magnesium alloy; mish-metal; microstructure; temperature; stress; creep