The effect of forging on microstructure and mechanical properties of in situ TiC/Ti composite

In this paper, 1 vol% TiC/Ti-1100 composite was prepared, and the beta transus temperature of the composite was measured using metallographic techniques. The composite was forged at 1173, 1333 and 1423 K, respectively. Microstructure of forged samples was studied by optical microscopy (OM) and transmission electron microscopy (TEM). The forging in the upper a phase field was investigated especially. Mechanical properties of the composite after hot forging were tested by tensile tests at ambient temperature. It was found that there is an about 100 K increase in transus temperature compared to monolithic Ti-1100 alloy. Widmanstatten microstructure, bimodal microstructure and microstructure containing aligned a plate were obtained after forging at various temperatures. Compared to Widmanstatten microstructure or bimodal microstructure, there is an increase about 200 MPa in ultimate tensile strength for the microstructure containing aligned alpha plate. The increase in tensile strength for the microstructure containing aligned alpha plate may result from two factors: one is the work hardening during the forging process, and the other is the interaction between alpha/beta interface and dislocations in a phase during tensile process.