Effect of deformation amount on the microhardness and element diffusion of the transition zone for Ti₃Al/TC11 by laser solid forming

The Ti₃Al/TC11 dual alloys were prepared by laser solid forming, and then were deformed by near isothermal forging with various deformation amounts. Afterwards, the effect of deformation amount on the microhardness and element diffusion of the transition zone and its two sides for the Ti₃Al/TC11 dual alloy specimen were investigated. The results show that after deformation, whatever the deformation amount is, the microhardness values of the transition zone and its two sides decrease obviously, the differences in microhardness value in the same specimen declines significantly and the distribution is more homogeneous. Thus, the deformation amount has a remarkable effect on the microhardness and element diffusion in the transition zone and its two sides. With the increase of deformation amount, all the values of the microhardness and the distribution homogeneity increase along the transition zone in the same specimen; however, the concentration gradients of the alloying elements including Ti, Al and Nb on both sides of the transition zone decrease, and they diffuse sufficiently along the joining interface. It is attributed to that with larger deformation, the coarse columnar grains formed in laser solid forming are broken sufficiently, the grain boundaries of β phases disappear, and the α and α₂ phases show the fine and equiaxed shape.