Microstructure evolution and mechanical properties of an ultra-high strength casting Mg-15.6Gd-1.8Ag-0.4Zr alloy

作者：Zhang, Yu; Wu, Yujuan^*; Peng, Liming; Fu, Penghuai; Huang, Fei; Ding, Wenjiang

来源：Journal of Alloys and Compounds, 2014, 615: 703-711.

DOI：10.1016/j.jallcom.2014.07.028

• Mg-Gd-Ag-Zr alloy
• Microstructure
• Precipitation
• Mechanical properties

An ultra-high strength casting Mg-15.6Gd-1.8Ag-0.4Zr alloy has been developed by conventional ingot metallurgy and heat treatment. The alloy exhibits outstanding ultimate tensile strength of 423 MPa and tensile yield strength of 328 MPa in the peak-aged condition. The main factors contributing to the ultra-high strength are the high number density of the prismatic beta' plates and basal gamma '' plates and their relative perpendicular distribution. Besides, a newly intermetallic compound is found in the as-cast microstructure other than Mg-5(Gd,Ag) compound. Although, the retained intermetallic compound at the grain boundaries in the alloy solution-treated at 480 degrees C for 18 h and at 500 degrees C for 8 h has a similar composition to Mg-5(Gd,Ag) compound, its crystal structure is demonstrated to be different to the two types of intermetallic compounds in the as-cast condition. Lastly, the effects of intermetallic compounds and precipitation phases on the fracture behavior of the alloy have been investigated, namely dominant inter-granular fracture in the as-cast and peak-aged conditions and mainly trans-granular fracture in the solution-treated condition.

• 出版日期2014-12-5
• 单位上海交通大学