High-Temperature Rheological Behavior and Microstructure Evolution of Mo-12Si-8.5B Alloy Reinforced by Layered Mo₂TiAlC₂ Phase

The rheological behavior of Mo-12Si-8.5B alloy reinforced by a layered Mo₂TiAlC₂ phase has been studied at temperatures ranging from 1200°C to 1400°C and strain rates ranging from 0.01 s⁻¹ to 0.0001 s⁻¹. The flow stress and microstructure evolution were investigated and the constitutive model was established. The results indicated that the Mo₂TiAlC₂ strengthens the Mo-12Si-8.5B alloy mainly by particle strengthening and grain boundary strengthening at high temperatures. With the increase of Mo₂TiAlC₂ content, the peak stress of the alloys improved. As the temperature increases or the strain rate decreases, the peak stress of the alloys decreases significantly. The microstructure reveals that the deformation of the Mo-12Si-8.5B-Mo₂TiAlC₂ alloy at high temperatures is mainly provided by the deformation of the α-Mo phase and grain boundary sliding. As the temperature rises to 1300–1400°C, the intermetallic phase gradually participates in the deforming but contributes less to the total deformation. Dynamic recovery and recrystallization greatly reduce dislocations at high temperatures. The Mo₂TiAlC₂ particles can inhibit recrystallization grain growth. In addition, the flow stress values of the Mo-12Si-8.5B-2 wt.% Mo₂TiAlC₂ alloy calculated by the constitutive model are in good agreement with the experimental values. Hence, it is reasonable to believe that the constitutive model can effectively predict the rheological behavior of alloys at high temperatures.