The Study On Alloying Effects And Difusion Theory Of Ti-Al Alloys With Cr And V

Ti-Al alloys is deal new-type heat structural material in aerospace and aviaTion aircraft, being used as Ni base superalloy low-temperature segment of the candidate materials, because of its properTies of low density department, good contravariance and oxidaTion resistance etc. But it is easy to sTick with grinding materials produced wear and limits its applicaTion scope when it is acted as sliding parts(such as the piston lock, the connecTing rod shaft and guide bar). The reason is its properTies of low hardness and poor wear resistance. Much research was studied on how to improve the Ti-Al alloy of department of hardness and abrasion resistance in the experiment, and has been achieved some successes. For example, Cr's alloying effect plays a main role to improve Ti-Al alloy of department of hardness and abrasion resistance. But its microscopic strengthening mechanisms and microcosmic diffusion principle is unclear. So how to simulate and expound this phenomenon from its atomic level is parTicularly important.The research of Ti-Al alloys with Cr,V addiTions was studied using the first-principle. Firstly, the electronic structures of Ti-Al alloys with Cr,V addiTions were studied using the first-principle. The total energy, formaTion energy, cohesive energy, the charge density and Density of statess were calculated, and explained the reason that the mechanical property was improved after infiltraTion chromium in Ti-Al alloys in terms of theory. The microscopic mechanism of Ti-Al alloys with Cr and V was explored through the charge density and Density of states distribuTion. The results of the study indicate that alloying element Cr and V occupied Ti atomic posiTion when being doped in Ti4Al4 and Ti4Al12. As the alloying element Cr content increasing, the structure stability increased after Cr was doped in Ti4Al4 and Ti4Al12. But it decreased after V was doped. The doping of V is trace in actual experiment, so the influence of the structure stability of composite compounds is not obvious. The department of mechanical properTies of Ti-Al alloys that included Shear modulus G, Young's modulus E and Body modulus B were greatly improved by the trace of alloying element Cr and V. The material of strength is closely related to Young's modulus E and Shear modulus G, the bigger of the value of G and E, the strength of the material and the better of the wear-resisTing performance.Secondly, the crystal structure opTimizaTion of the building of the Ti-Al alloy (100) plane was also studied. The department of the diffusion of the Ti-Al alloy (100) plane with Cr and V was systermaTically studied. The strengthening mechanisms of Ti-Al alloy with Cr and V were analyzed from the electronic structure. The reason of the properTies improving of Ti-Al alloy with Cr and V was explained in theory. The alloying element Cr or V priority occupied second Ti atomic posiTion when it doped in Ti5Al5 and Ti5Al15, and their structures' stability was best. The two alloying elements Cr or V preferred simultaneously occupied the second and third floor Ti atomics'posiTion when their doped in Ti5Al5 and Ti5Al15, and their structures'stability was best. The reason through analyzing is that the addiTion of Cr in the alloys enhanced reciprocal hybridizaTion of Cr(3d),Al(3p) and Ti(3d), while V in the alloys enhanced reciprocal hybridizaTion of V(3d,Ti(3d) and Al(3p), and the alloys'binding capacity increased.