Wetting of B4C by molten Ni-Ti alloys at 1753Â K

We investigated the wetting of B4C by molten Ni-Ti alloys at 1753 K using a modified sessile drop method. The improved final wettability and the interface microstructure evolution were observed with the increasing of Ti addition. The mechanism of improvement can be mainly ascribed to the formation and distribution of reaction product TiB2 at liquid-solid interface. Generally, the spreading was driven by the reaction at liquid-solid interface. For Ni-10 at.% Ti/B4C, with the dissolution of substrate (i.e., the accumulation of B in liquid) at first, the system then breaking through the thermodynamic conditions for the precipitation of a continuous reaction product layer, and a distinctive bimodal interface was observed finally. The addition of Ti, as a surface-active element, reduced the initial contact angle, and the dissolved B also segregate at surface, and then reduced the final contact angle.