Pseudopartial wetting of W/W grain boundaries by the nickel-rich layers

Abstract

The excellent properties of heavy tungsten-based alloys are based on the combination of hardness of W grains, as well on the toughness and ductility of the binder with low melting temperature (usually containing nickel, iron, or copper). The topology (and resulting properties) of binder network are controlled by the complete and incomplete wetting of W/W grain boundaries (GBs) and GB triple junctions (TJ). We observed for the first time that pseudoincomplete (or pseudopartial, or frustrated complete) GB wetting by Ni layers is also present in W–Ni alloys. Namely, the channel of a Ni-rich solid solution in GB TJ forms the non-zero dihedral contact angle not only with “dry” W/W GBs (incomplete GB wetting), but also with W/W GBs containing the uniformly thin (3nm) Ni-rich layer (pseudoincomplete GB wetting).