Deformation and fracture properties of damage tolerant in-situ titanium matrix composites

This paper discusses the tensile response and fracture toughness of in-situ titanium alloy metal matrices discontinuously-reinforced with whiskers of titanium boride which were successfully produced by ingot metallurgy techniques. Additions of elemental boron resulted in a near uniform dispersion of the rod-like titanium boride (TiB) reinforcements in the alloy matrix. Such composites have engendered considerable scientific and technological interest due to their attractive combinations of improved mechanical properties and low manufacturing cost. The improved elastic moduli of the composites are explained using shear lag and rule-of-mixtures theories. The increased strengths of the in-situ composites are rationalized by considering the combined effects of deformation restraints imposed by the stiff whiskers and strengthening contributions arising from the substructure that evolves from the presence of additional dislocations.