Microstructure of MgAl5Ca3Sr alloy after creep deformation and high-temperature heat treatment

作者：Rzychon T^*

来源：Materialwissenschaft und Werkstofftechnik, 2014, 45(5): 344-353.

DOI：10.1002/mawe.201400233

• Magnesium alloys
• Mg-Al-Ca-Sr alloys
• microstructural stability
• microstructure
• creep properties

The paper presents results of microstructural investigations of MgAl5Ca3Sr magnesium alloys in the as-cast condition, after creep tests at 180 degrees C, and after heat treatment at 450 degrees C for 4.5 hours. The microstructure of MgAl5Ca3Sr alloy is composed of alpha-Mg solid solution, irregular shaped (Mg, Al)(2)Ca phase with C36 crystal structure, bulky (Mg, Al)(17)(Sr, Ca)(2) phase, fine lamellar Mg2Ca phase with C14 structure, needle-shaped Al2Ca precipitates with the C15 crystal structure. The precipitation of the needle-shaped Al2Ca phase in the alpha-Mg grains and spheroidization of the C14 phase were found after heat treatment at 450 degrees C in argon atmosphere. The (Mg, Al)(2)Ca (C36) and (Mg, Al)(17)(Sr, Ca)(2) phases seems to be stable at 450 degrees C, however, the increasing of aluminum content in C36 compound was observed suggesting the initial stage of C36 -> C15 transformation. After creep deformation at 180 degrees C precipitates of the Al2Ca phase were found in alpha-Mg phase. The intermetallic compounds are stable at 180 degrees C. The MgAl5Ca3Sr alloy exhibits good creep resistance up to 75 MPa. Tensile properties are comparable to those of Mg-RE-Zn-Zr alloys.

• 出版日期2014-5