Mechanical and Physical Characterizations of a Three-Phase TiAl Alloy during Near Isothermal Forging

TiAl alloy is a high temperature structural material with excellent comprehensive properties in the range of 750-900 degrees C. However, its engineering application is limited by its poor plasticity and hot working properties at room temperature. Based on the above background, a novel three-phase Ti-40Al-6V-1Cr-0.3Ni (at.%) alloy was designed and fabricated in the present study. The as-cast ingot was subjected to near-isothermal forging, and the thermoplastic deformation behavior, microstructure evolution and mechanical properties were systematically studied. Near-isothermal forging shows excellent forming capability, and the forging disk is flawless without cracking. The core of the forging disk shows the greatest degree of deformation, and the microstructure is composed of fine equiaxed grains and residual (alpha 2/gamma) lamellae. The hardness of the B2 phase and the hardness difference between the B2 phase and gamma phase are reduced by the Cr and V elements added in the alloy. The wrought alloy exhibits excellent mechanical properties at room temperature and elevated temperature, respectively. The uniform fine microstructure, low nanohardness of the B2 and gamma phase and the property matching of each phase can be accounted for the excellent mechanical properties.

Automated summary

A novel TiAl alloy was designed and fabricated in this study, and its thermoplastic deformation behavior, microstructure evolution, and mechanical properties were systematically studied during near-isothermal forging. The results showed that the alloy exhibited excellent mechanical properties at both room temperature and elevated temperature, attributed to the flawless forging disk without cracking, the microstructure composed of fine equiaxed grains and residual (alpha 2/gamma) lamellae, and the reduced hardness of the B2 phase and the hardness difference between the B2 and gamma phase due to the addition of Cr and V elements.