Premium
Microstructure of MgAl5Ca3Sr alloy after creep deformation and high‐temperature heat treatment
Author(s) -
Rzychoń T.
Publication year - 2014
Publication title -
materialwissenschaft und werkstofftechnik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.285
H-Index - 38
eISSN - 1521-4052
pISSN - 0933-5137
DOI - 10.1002/mawe.201400233
Subject(s) - microstructure , materials science , intermetallic , creep , alloy , precipitation , lamellar structure , phase (matter) , metallurgy , ultimate tensile strength , deformation (meteorology) , crystal (programming language) , composite material , chemistry , physics , organic chemistry , meteorology , computer science , programming language
The paper presents results of microstructural investigations of MgAl5Ca3Sr magnesium alloys in the as‐cast condition, after creep tests at 180 °C, and after heat treatment at 450 °C for 4.5 hours. The microstructure of MgAl5Ca3Sr alloy is composed of α‐Mg solid solution, irregular shaped (Mg,Al) 2 Ca phase with C36 crystal structure, bulky (Mg,Al) 17 (Sr,Ca) 2 phase, fine lamellar Mg 2 Ca phase with C14 structure, needle‐shaped Al 2 Ca precipitates with the C15 crystal structure. The precipitation of the needle‐shaped Al 2 Ca phase in the α‐Mg grains and spheroidization of the C14 phase were found after heat treatment at 450 °C in argon atmosphere. The (Mg,Al) 2 Ca (C36) and (Mg,Al) 17 (Sr,Ca) 2 phases seems to be stable at 450 °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 °C precipitates of the Al 2 Ca phase were found in α‐Mg phase. The intermetallic compounds are stable at 180 °C. The MgAl5Ca3Sr alloy exhibits good creep resistance up to 75 MPa. Tensile properties are comparable to those of Mg‐RE‐Zn–Zr alloys.