Abstract:

The dissolution behavior of solid nickel in static liquid zinc containing Fe at 450 ℃ was studied by using optical microscopy , SEM and EDS , and the controlling mechanism of dissolution rate of solid nickel was analyzed according to the dimensionless correlation for mass transfer with natural convection and the dissolution rate model which takes into account the formation of intermetallic compound layers. The results show that (1) similar to that in pure liquid Zn , the dissolution of solid Ni in liquid Zn containing Fe may result in the formation of γ-Ni₂ Zn₅ and δ-NiZn₈ phase layers; (2) some Γ₂ -Fe₅ Zn₆ Ni ₈₉particles may form in the liquid near the solidJliquid interface due to the existence of Fe; and (3) the dissolution process of Ni in the liquid Zn unsaturated with Fe is similar to that in pure liquid Zn and is governed by a mixed control mechanism involving the diffusion of nickel atom in Ni-Zn alloy layers and the chemical reaction at the interfaces , while the dissolution rate of Ni in the liquid Zn supersaturated with Fe is mainly controlled by the diffusion of Ni atom across a concentration boundary layer. It is thus concluded that the existence of Fe in liquid Zn accelerates the dissolution of solid Ni.

Key words: solid phase, liquid metal, dissolution, nickel, zinc