Microstructures and tensile properties of directionally solidified Ti-45Al-2Cr-2Nb alloy by electromagnetic cold crucible zone melting technology with Y2O3 moulds

In this study, a Ti-45Al-2Cr-2Nb alloy was directionally solidified by electromagnetic cold crucible zone melting technology with Y2O3 moulds, and the effects of growth rate and heating power on microstructural evolution and tensile properties were investigated. In the directionally solidified regions, microstructures were mainly composed of well-aligned α2/γ lamellae and B2 phases as well as Y2O3 particles. Higher growth rates and heating powers refined the lamellae. In addition, the angle of the lamella orientation to the growth direction increased with a higher growth rate and a lower heating power, but the amount of Y2O3 particles was reduced. Appreciable tensile properties, including an ultimate tensile strength of 576 MPa, a yield strength of 511 MPa, and an elongation of 1.1% were achieved at optimal solidification parameters. Moreover, Y2O3 particles significantly affected the tensile properties, because they were found to act as crack sources.