Orientation dependence of mechanical property and microstructure in molybdenum alloy single crystals at the high strain rate

The dynamic mechanical behavior and microstructure evolution of molybdenum single crystals with different orientations at the high strain rate have been investigated and disclosed comprehensively. The dynamic mechanical behavior exhibits a strong crystal orientation dependence, with the <111> orientation showing the highest average flow stress and work hardening rate, followed by the <110> orientation, with the <112> orientation being the lowest. To clarify the orientation dependence of microstructure evolution, EBSD and TEM analyses were performed. The dislocations struggle to cross the boundaries of dislocation cells for the <111>-oriented single crystal, resulting in a high work hardening rate, which is mainly manifested as adiabatic shear bands and a small number of twins. For the <110> orientation, the dislocation is blocked by dislocation walls, and more twins are generated to accommodate the deformation. The dislocation movement is significantly hindered in the <112> orientation, and the {112}<111> twins are completely formed. The dynamic recrystallization occurs in the adiabatic shear bands of the <110> orientation, and the preferred rotation of the crystal lattice is the main recrystallization mechanism.