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

The compression rheological behavior of Mo-12Si-8.5B alloy reinforced by layered Mo₂TiAlC₂ phase is studied at temperatures ranging from 1200℃ to 1400℃ and strain rates ranging from 0.01s^-1 to 0.0001s^-1. The trend of flow stress and microstructure evolution was investigated. The results show 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 alloy improved by 43.8% at most. With the increase of test temperature or the decrease of strain rate, the peak stress of alloys decreases significantly. The microstructural observations reveal that the deformation of Mo-12Si-8.5B-Mo₂TiAlC₂ alloy at high temperatures is mainly provided by the plastic deformation of the soft α-Mo phase and grain boundary sliding. As the temperature rises to 1300℃-1400℃, the intermetallic phase gradually participates in the deforming, however, it contributes less to the total deformation, while dynamic recovery and recrystallization greatly reduce dislocations, and the deformed α-Mo grains are re-equiaxed. The Mo₂TiAlC₂ particles can inhibit dynamic recrystallization grain growth to some extent.