Dynamic recrystallization behavior and strengthening mechanism of a novel Mo–Ti₃AlC₂ alloy at ultrahigh temperature

Increasing the recrystallization temperature to achieve better high-temperature performance is critical in the development of molybdenum alloys for ultrahigh-temperature applications, such as the newest generation of multitype high-temperature nuclear reactors. In this study, an innovative strategy was proposed to improve the performance of molybdenum alloys at high temperature by using the two-dimensional MAX (where M is an early transition metal, A is an A-group element and X is C or N) ceramic material Ti₃AlC₂. The relationships between flow stress, strain rate and temperature were studied. The microstructure, distribution of misorientation and evolution of dislocations in the Mo–Ti₃AlC₂ alloy were analyzed. The microscopic mechanism of the Ti₃AlC₂ phase in the molybdenum alloy at high temperatures was clarified. The experimental results showed that the peak flow stress of Mo–Ti₃AlC₂ at 1600 °C reached 155 MPa, which was 161.8% greater than that of pure Mo. The activation energy of thermal deformation of Mo–Ti₃AlC₂ was as large as 537 kJ·mol⁻¹, which was 17.6% more than that of pure Mo. The recrystallization temperature reached 1600 °C or even higher. The topological reaction of the Ti₃AlC₂ phase consumed a large amount of energy at high temperatures, resulting in increases in the deformation activation energy. Nanolayer structures of AlTi₃ and Ti–O Magnéli-phase oxides (Ti_nO_2n-1) were formed in-situ, which relied on kink bands and interlayer slip, resulting in many dislocations during deformation. Therefore, the special two-dimensional of the structure Ti₃AlC₂ ceramic inhibited the recrystallization behavior of the Mo alloy. The results of this study can provide theoretical guidance for the development of a new generation of molybdenum alloys for use in ultrahigh-temperature environments.