Deformation Behavior and Microstructure Evolution of a TiB-Reinforced Ti-6.5Al-2Zr-1Mo-1V Matrix Composite

A Ti-6.5Al-2Zr-1Mo-1V/TiB metal-matrix composite with 10.0 vol.% of TiB reinforcing fibers was produced using vacuum arc melting and compared with an unreinforced arc-melted Ti-6.5Al-2Zr-1Mo-1V alloy. The initial microstructure of the composite consisted of two-phase alpha + beta matrix with randomly distributed boride fibers. The addition of TiB fibers resulted in a 40% increase in strength. At room temperature, the composite attained a yield strength of 1100 MPa and a ductility of 10% in compression. At elevated temperatures (400-950 degrees C), the values of yield strength of the composite remained similar to 1.5-2 times greater in comparison with the unreinforced alloy. A faster development of globularization in the composite in comparison with the unreinforced alloy was established. The interphase TiB particle/matrix boundary did not contain either a transition layer or any defects like pores or microcracks. Using the obtained results, the apparent activation energy of the plastic deformation was calculated, and processing maps were analyzed both for the unreinforced alloy and for the composite.