Strengthening the grain boundary of Mo alloy via little TiC addition

The little TiC was added into Mo alloys by facile ball milling and subsequent sintering. Interestingly, ultrafine Mo-TiC alloy (6.53 & mu;m) possesses quasi-cleavage transgranular fracture morphology, which is differed from traditional intergranular fracture morphology of oxide-dispersion-strengthened molybdenum (ODS-Mo) alloy. The alloy interface with the lowest strength changes from Mo grain boundaries (GBs) to grain interior, hence the crack propagates along grain interior. For one thing, some C-deficient TiC (Ti8C5) can adsorb adjacent impurity oxygen at sintering stage to generate in-situ TiOx, thereby purifying Mo matrix. For another thing, coherent interfaces between TiC/TiOx particles and Mo further strengthen Mo matrix. Moreover, a lot of TiC/TiOx particles within Mo grains could efficaciously accumulate dislocations and indirectly improve GBs strength. Compared to ball-milled Mo or ODS-Mo alloy reported in literatures, the sintered Mo-TiC alloys in present work possess a high hardness (468 HV0.2), an excellent match of high strength (1287.3 MPa) and large ductility (18.1%).