Effect of Cr on the wetting in Cu/graphite system

The isotherm wetting and spreading behaviors of the molten Cu-Cr alloys with 0.5, 1.0 and 2.0 at.% Cr on porous graphite substrates were investigated at 1373 K in a flowing Ar atmosphere using a modified sessile drop method. The wettability improves with increasing Cr content in the alloy as a result of phase transition from Cr3C2 to more wettable and metallic-like Cr7C3 developed at the interface. The spreading kinetics are controlled by the interfacial reaction in the early stage and the diffusion of Cr from the drop bulk to the triple junction in the later stage together with a transition in the intermediate stage.

Research highlights► The wettability improves with increasing Cr content in the alloy as a result of phase transition from Cr3C2 to more wettable and metallic-like Cr7C3 developed at the interface of the Cu-Cr/graphite system. ► The spreading kinetics is controlled by the interfacial reaction in the early stage and the diffusion of Cr from the drop bulk to the triple junction in the later stage together with a transition in the intermediate stage. ► The different effects of Cr and Ti on the wetting in the Cu/graphite system are primarily attributed to their different activities in liquid Cu.