Influence of Heat Treatment on Microhardness and Microstructure of the Joining Interface for Ti-24Al-15Nb-1.5Mo/TC11

Abstract

The microhardness and microstructure of Ti-24Al-15Nb-1.5Mo/TC11 dual alloy joining interface processed by different heat treatment regimes were investigated. The results show that the microhardness of the weld zone and Ti-24Al-15Nb-1.5Mo alloy side of the dual alloy processed by gradient heat treatment are higher than that of the specimen processed by balance heat treatment. Moreover, the microstructure differences between the specimens processed by gradient heat treatment and balance heat treatment are very obvious, particularly in the interface between the TC11 alloy and the weld zone. While the joining interface is processed by gradient heat treatment, the microstructure change homogeneously, and the demarcation lines are ambiguous. However, for the joining interface processed by balance heat treatment, the demarcation lines are very obvious, and the microstructure of the TC11 alloy side is bi-morphic, the lath is short and coarse. Therefore, the interface integrity of the dual alloy processed by gradient heat treatment is better, which is an adoptable method to improve the properties of the dissimilar alloy joining interface.