Functionally Graded WC-Co/WC-Fe-Ni Double-Layer Cemented Carbides

We investigated the properties of functionally graded WC-based cemented carbide prepared with a new approach featured by sintering the WC-Co/WC-Fe-Ni double-layer compacts together. For this approach, the reasonable pressing pressure to prepare the alloys should be about 15 MPa, under which the two layers have consistent sintering shrinkages and the unexpected phenomena (e.g. layering and cracking) was not observed. The phase composition and microstructure analyses based on the X-ray diffraction, optical and scanning electron microscopy experiments indicate that the η or graphite phase does not exist in both WC-Co and WC-Fe-Ni layers, and that the interface of these two layers is well combined together. Meanwhile, a significant gradient of Fe, Ni and Co is observed at the interface between the above two layers, and this composition gradient results in a noticeable hardness gradient, which further leads to the WC-Co/WC-Fe-Ni double-layer cemented carbide being of high hardness, wear resistance and toughness. Copyright © 2020, Northwest Institute for Nonferrous Metal Research. Published by Science Press. All rights reserved.