Hierarchical Fe6W6C enabling ultra-strong porous tungsten

Abstract

Porous tungsten is a promising candidate in the nuclear industry. Decreasing the relative density of tungsten could optimize its performance and workability but also strongly weaken its mechanical properties. In this work, Fe6W6C is employed by an in situ reaction and forms a hierarchical microstructure that includes both amorphous and crystalline states. The crystal Fe6W6C distributed around W grains maintains a coherent relationship with W, while the amorphous state Fe6W6C fills the gap and sintering neck at a low-temperature heat treatment, resulting in a dense ligament structure. The hierarchical Fe6W6C achieves the enhancement of the interfacial strength and the crack suppression at the same time, including changing the crack initiation mode as well as the propagation path. As a result, the porous tungsten exhibits a remarkable enhancement and presents stretch-dominated behaviour with a high structural efficiency. The in situ Fe6W6C strengthened ligament attains a maximum strength of 780 MPa, demonstrating the considerable structural advantages in ligaments.