Tensile deformation and fracture behaviour of a titanium-alloy metal-matrix composite

In this paper, the microstructure, tensile behaviour and quasi-static fracture characteristics of a Ti-6Al-4V alloy reinforced with discontinuous whiskers of titanium boride, are presented and discussed. Microstructural analysis of the composite revealed a non-uniform dispersion of the whisker reinforcements in the Ti-6Al-4V matrix. The elastic modulus of the composite was better than that of the unreinforced matrix. The ambient-temperature yield strength of the Ti-6Al-4V/TiB composite was higher than the yield strength of the unreinforced matrix. The strength decreased with increase in test temperature. The increased strength of the composite is rationalized in terms of concurrent and mutually interactive influences of mechanisms based on work hardening and the substructure that evolves from the presence of additional dislocations. The intrinsic mechanisms and micromechanisms governing the tensile fracture process are discussed. (C) 1997 Elsevier Science Limited.