Abstract
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 per-formance 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 ℃ 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 ℃ 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(TinO2n-1)were formed in-situ,which relied on kink bands and interlayer slip,resulting in many dislocations during deformation.Therefore,the special two-dimen-sional of the structure Ti3AlC2 ceramic inhibited the recrystallization behavior of the Mo alloy.The results of this study can provide theoretical guidance for the devel-opment of a new generation of molybdenum alloys for use in ultrahigh-temperature environments.
基金项目
National Key R&D Program of China(2020YFB2008400)
Key Technology and Development Program of Henan Province(232102231024)
万方数据