Microstructural evolution and mechanical properties of TiC-containing WC-based cemented carbides prepared by pressureless melt infiltration

WC-based cemented carbides with different amounts of TiC (0.9, 1.2, 1.5, 1.8 and 2.1 wt%) were synthesized by pressureless melt infiltration at 1200 degrees C for 90 min in vacuum furnace using Cu-10Ni-5Mn-3Sn binder alloy and cast WC, Ni and TiC powders. The microstructural evolution, new phase formation, and related mechanical properties of melt infiltrated alloys were investigated. Results revealed that partially-cast WC and TiC decom-posed and formed Ni2W4C, W, (Ti,W)C1-x and annular-structured solid solution when the content of TiC was in the range of 1.2-2.1 wt%, whereas Ni2W4C and W were not observed in the alloy with 0.9 wt% TiC. Annular -structured solid solution was characterized by high carbon with relatively small amounts of W and/or Ti. An increase in TiC content promoted the formation and growth of Ni2W4C and (Ti,W)C1-x phases. However, the annular structure with a continuous network developed into discontinuous net-like distribution and gradually disappeared. Addition of an appropriate amount of TiC improved the Rockwell hardness (HRA) and transverse rupture strength (TRS); however, the impact toughness always decreased with the addition of more amount of TiC. The alloys with 1.8 wt% TiC, 1.5 wt% TiC, and 0.9 wt% TiC exhibited the best mechanical properties with Rockwell hardness of 93.6 HRA, TRS of 1823.4 MPa, and impact toughness of 6.33 J cm-2, respectively.