Thermodynamic Simulation And Microstructure And Properties Of Ti-48Al-2Cr-2Nb And Ti-48Al-8.5Nb

Ti Al alloy has been widely concerned because of its low density,high modulus of elasticity,high temperature resistance,oxidation resistance and creep resistance.In this paper,Ti-48Al-8.5Nb is designed as the matrix material with a certain amount of nano Y₂O₃,aiming at the shortcomings of low ductility at room temperature and poor molding performance of Ti Al Based intermetallics,and poor wear resistance and oxidation resistance at high temperature Two kinds of ingots,Ti-48Al-8.5Nb and Ti-48Al-8.5Nb-0.05Y₂O₃,were obtained by melting and casting 3 particles.The microstructure,room temperature and high temperature mechanical properties of the ingots were mainly studied.The effects of alloy elements and nano Y₂O₃ particles on the properties and structures were explored and the heat treatment process plan suitable for titanium aluminum alloy was found.The phase composition and microstructure of as cast high alloy were analyzed by SEM and EDS.the mechanical properties of the alloy were tested by Instron 5569 electronic universal material testing machine.In the as cast state,Ti-48Al-8.5Nb and Ti-48Al-8.5Nb-0.05Y₂O₃ alloys are mainly composed of ??Ti Al?,? 2?Ti3Al?and ? / B2 phases.The microstructure is mainly composed of ? / ? 2 two-phase distribution alternately.? / B2 phase is distributed at the junction of grain boundary,and the structure segregation is serious,showing network distribution.After adding nano Y₂O₃ particles,nano Y₂O₃ grew up and segregated,which was basically distributed in segregation and grain boundary,showing rod or fishbone shape.At room temperature,the tensile strength of Ti-48Al-8.5Nb-0.05Y₂O₃ is compared with that of Ti-48Al-8.5Nb.After adding nano Y₂O₃ particles,the tensile strength increases and the elongation is slightly larger.At the same time,the tensile fracture analysis shows that all of them are brittle fracture.At the same time,the lamellar composition of the alloy becomes finer with the addition of Y₂O₃ nanoparticles.use jmatpro software calculated the thermodynamic curves of Ti-48Al-8.5Nb-0.05Y₂O₃ and Ti-48Al-8.5Nb alloys,calculated and simulated the strength and hardness of the two alloys at room temperature,as well as the mechanical properties at high temperature,and calculated the creep behavior of the two alloys at 800 ? and 900 ?,the creep behavior can be divided into three stages: the first stage is the initial creep stage,the second stage is stable The third stage is accelerated creep stage.According to the thermodynamic and dynamic curves of the two alloys,the appropriate heat treatment process is designed.The results show that the addition of Nb element can reduce the mechanical properties at room temperature,but slightly improve the mechanical properties and creep properties at high temperature.