Fe对Ti-6Al-4VELI合金力学性能的影响

he effect of different Fe contents (0.03%, 0.17%, 0.24%) on the mechanical properties of Ti-6Al-4V ELI (TC4 ELI) alloy was studied. The microstructures were characterize by using EBSD, and the tensile properties, fracture toughness and fatigue crack growth rates (da/dN), creep properties of TC4 ELI with three Fe contents were compared and analyzed. The results showed that with the increase of Fe contents, Fe has no apparent influence on fracture toughness, however, tensile strength of the alloy was improved. The da/dN of the three TC4 ELI alloys were found to be almost identical at room temperature and 200, however da/dN was found to be marginally faster as Fe contents increased at 400. Within the range of 250~350, Fe improved creep resistance, while from 350 to 400, Fe had opposite effect. Fe atom was mainly enriched in phase. And the tensile strength was improved with the increase of Fe contents due to the solid solution strengthening effect. Because of the high diffusing rates of Fe atom under the condition of 400, the movement of matrix atoms and interfaces were accelerated. So that, the resistance to dislocation motion in crack tip plastic zone was reduced, which led to higher da/dN. Under the condition of 350-400, Fe could improve the creep rate by speeding up the process of dislocation climbing, but the reinforcement is more important below 350 because of the weak diffusion.