Creep rupture behaviors of a laser melting deposited TiC/TA15 in situ titanium matrix composite

The creep rupture behaviors of a laser melting deposited in situ TA15 titanium matrix composite reinforced by 10.8 vol.% TiC particulates were investigated at 873 and 923 K. The as-deposited TiC reinforcements were mainly in near-equiaxed and coarse dendritic with a stoichiometry of TiC_0.71. The composite exhibited a superior creep resistance to the monolithic titanium alloy. The creep rupture mechanism was dominated by a mixture of particle cracking, interface debonding and interparticle voiding. Voids nucleated at broken particles, debonded interfaces and interparticle matrix at the initial stage of rupture. The growth, coalescence and transverse linkage of these voids through the matrix contributed to the final failure of the composite. The strengthening in creep resistance of the composite was mainly attributed to the load transfer from the matrix to the particle reinforcements and the refinement of the Widmanstätten matrix.