WC-18 wt.% Co with simultaneous improvements in hardness and toughness derived from nanocrystalline powder

Most materials exhibit a decreased toughness as the hardness (or strength) increases. Here we report a new strategy to combat this problem for cemented carbides (WC-Co). Instead of suppressing the growth of WC grains during sintering, we allow nano-WC particles to grow in a controlled manner, leading to the formation of thin WC platelets with a high aspect ratio. The thin thickness offers high hardness, while the high aspect ratio provides superior toughness. As a result, the bulk WC-Co produced from the nanocrystalline powder bucks the unfavorable trend exhibited by most of the cemented carbides available today – showing simultaneous improvements in hardness and toughness. The principle discovered in this study has significant impact on WC-Co and offers new opportunities to obtain superior mechanical properties for other cermets and advanced ceramics as well.

► We report a new strategy to enhance toughness and hardness of cemented carbides. ► Simultaneous enhancement is achieved via thin WC platelets with high aspect ratio. ► Thin WC platelets are formed via controlled growth of nano-WC particles. ► High hardness is derived from the thin thickness of WC platelets. ► Superior toughness is attained from the high aspect ratio.