Mechanical Properties and Microstructure of Twin-Roll Cast Mg-Zn-Y Alloy

Abstract

Mg_97.3Zn_2.3Y_0.4 alloy has been subjected to twin-roll casting (TRC) process. As-cast microstructure consists of α-Mg dendrite and icosahedral interdendritic phase. The icosahedral phase present in TRC alloy is found to be thermally unstable and transforms to H-phase and W-phase during subsequent thermo-mechanical treatment (TMT) at 400°C. It shows that the pre-heating condition has a significant effect on the microstructural evolution during TMT. The specimen pre-heated at 400°C for 30 min shows elongated microstructure after TMT, while the specimen pre-heated at 400°C for 12 h shows equiaxed recrystallized structure after TMT. Such homogeneous microstructure of the specimen pre-heated at 400°C for 12 h results in better combinations of strength and ductility than the specimen pre-heated at 400°C for 30 min.