High temperature deformation and in situ fracture measurements to understand grain size/binder effects in hardmetals

该项目的目的是研究微观结构和粘结剂化学对界面特性在裂纹扩展中的作用。已经确定了组成材料的不同类型的WC/WC晶界(根据CSL)。围绕这些边界制作双悬臂梁(DCB)的工作正在进行，目的是了解界面特性。对WC单晶和大颗粒WC(~20-100微米)进行了DCB实验，作为界面研究的基础，以此为契机测定了WC晶面的表面能，并与文献中的密度泛函理论计算结果进行了比较。未来的工作将是研究具有钴渗层或铬层的WC/WC边界。在蠕变过程中，由于晶界滑动，WC/WC钴渗入。添加铬是为了抑制颗粒的生长。

The aim of the project is to examine the role of microstructure and binder chemistry on interface properties in crack growth. Different types of WC/WC grain boundaries (in terms of CSL) making up the material have been identified. Work is being done to fabricate double cantilever beams (DCB) around these boundaries with the objective of understanding interface properties. DCB tests have been performed on WC single crystals and large WC grains (~20-100 microm) as a basis for interface study: this is to be used as an opportunity to determine the surface energies of WC crystallographic planes and compare with density functional theory calculations from the literature. Future work will be concerned with studying WC/WC boundaries with cobalt infiltration or chromium layers. WC/WC cobalt infiltration occurs during creep due to grain boundary sliding. Chromium is added to inhabit grain growth.