Hot compression behavior and recrystallization mechanism of 1.5 wt% Ti3AlC2 ceramic-enhanced Mo alloys with two-dimensional layers

Abstract

Improving the high temperature strength of Mo alloys is a key problem to expand the application range of Mo alloys. In this study, the Mo-1.5 wt%Ti3AlC2 alloy was designed by introducing new two-dimensional (2D)-layered ceramic particles Ti3AlC2 into Mo. The peak flow stress of the Mo-1.5 wt%Ti3AlC2 alloy reaches 308 MPa at 1200 °C. The diffusion activation energy Q of the Mo-1.5 wt%Ti3AlC2 alloy is as high as 533.38 kJ/mol, which is higher than that of pure Mo (480 kJ/mol). Sintering in the reducing atmosphere of hydrogen at high temperature, the Ti3AlC2 consumes a large amount of energy to form AlTi3 and Ti5O9, which leads to an increase in the diffusion activation energy. We have established the constitutive equation of the Mo-1.5 wt%Ti3AlC2 alloy, and studied the microstructure evolution and deformation mechanism under hot compression. The results show that the stress index of n1 > 3 indicates that the plastic deformation mechanism was a dislocation mechanism. With the addition of Ti3AlC2, a large number of dislocations were produced in the alloy at the early stage of hot deformation. With increasing temperature, the dislocation entanglement gradually cancels out, resulting in the decrease of dislocation density. With the increase of temperature and deformation rate, the dynamic recrystallization (DRX) mechanism of the Mo-1.5 wt%Ti3AlC2 alloy was mainly continuous dynamic recrystallization (CDRX) at 1200 °C/0.01 s−1 and discontinuous dynamic recrystallization (DDRX) at 1600 °C/10 s−1. This work provides a new research direction for designing high performance Mo alloys.