Application of post-sintering carburization process in forming cobalt gradient in ultrafine grained wc-Co composites

摘要

Cemented tungsten carbide (WC-Co) with ultrafine grained microstructure or functionally graded microstructure has attracted interests in the field of WC-Co over the past several decades. To obtain the fine grain microstructure, it is typical to add grain growth inhibitors to prevent coarsening of WC grains. However, the use of such additives results in a decrease in the fracture toughness of WC-Co materials. The development of functionally graded WC-Co with Co compositional gradient offers a potential solution by combining both high hardness and high toughness in a single WC-Co component. The Co gradient can be produced via a post-sintering carburization heat treatment process that has been developed recently. This carburization heat treatment process was demonstrated successful in producing gradient in the straight WC-Co alloys without other additions. The purpose of this study is to demonstrate that this post-sintering carburization process is also applicable for the ultrafine grained WC-Co alloys with grain growth inhibitors.