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

Abstract

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⋅m1/2 at the surface to 13.34 MPa⋅m1/2 in the core. The present results show that FGCCs with high outer layer hardness and high inner layer toughness were successfully prepared.