Fabrication of graded WC-Ni₃Al cemented carbides by lamination pressing and spark plasma sintering

WC-Ni₃Al composite powders with different Ni₃Al contents were prepared by ball milling WC and Ni₃Al powder mixtures. Functionally graded WC-Ni₃Al cemented carbides (FGCCs) with Ni₃Al content gradient were prepared by lamination pressing different WC-xNi₃Al (x = 2, 10) powder mixtures and spark plasma sintering the layered compacts. The results show that there are some distinct gradient composition layers in the sintered bulk sample. With the increase of Ni₃Al content, the size of the WC grains decreases from 0.83 to 0.74 μm because Ni₃Al increases the free path of WC grains. And due to difference in Ni₃Al content and WC grain size, graded WC-Ni₃Al cemented carbides has a Vickers hardness of 1901.8 HV30 at the surface, which decreases to 1780.3 HV30 in the core. Nevertheless, the fracture toughness increases from 10.89 MPa⋅m^1/2 at the surface to 13.34 MPa⋅m^1/2 in the core. The present results show that FGCCs with high outer layer hardness and high inner layer toughness were successfully prepared.