High temperature mechanical properties and strain hardening mechanism of directionally solidified Mg-Gd-Y alloy

The Mg-6.0Gd-0.5Y alloy, with straight grain boundaries and preferred growth orientation [224( )3], was prepared by directional solidification. The microstructure evolution during tensile tests at 150-350 degrees C was investigated using Electron Back-Scattered Diffraction (EBSD) and High-Resolution Transmission Electron Microscopy (HRTEM). Subsequently, the relationship between the deformation mechanism and mechanical properties was discussed. The results show that there are obvious uniform plastic deformation stage and work hardening stage after yield for the tensile stress-strain curves of the Mg-6.0Gd-0.5Y samples tested at 150 degrees C-250 degrees C, while evident dynamic recrystallization characteristic can be observed for the curve of the sample tested at 350 degrees C. It is found that the stable high-temperature strength of the Mg-6.0Gd-0.5Y alloy can be attributed to the delayed dynamic recrystallization, the formation of compression twins and I1-type stacking faults. In addition, the superior plasticity of the alloy is related to the high concentration of crystal orientation, the activation of tensile twins, and non-basal slip which can provide more than 5 independent systems.

Automated summary

The microstructure evolution of Mg-6.0Gd-0.5Y alloy during tensile tests at different temperatures was investigated using EBSD and HRTEM. It was found that the high-temperature strength of the alloy is attributed to delayed dynamic recrystallization, compression twins, and stacking faults, while the superior plasticity is related to high crystal orientation concentration, tensile twins activation, and non-basal slip.