固相Ni在含Fe液相Zn中的溶解行为

Dissolution Behavior of Solid Nickel in Liquid Zinc Containing Fe

利用金相显微镜、扫描电镜及能谱分析研究了固相Ni在450℃静止的含Fe液相Zn中的溶解行为,并利用自然对流下的质量传输准数方程和考虑金属间化合物层形成的溶解速率模型,分析了固相Ni在含Fe液相Zn中的溶解速率控制机制.结果表明:固相Ni浸入含Fe液相Zn中会形成与纯液相Zn中相似的γ-Ni2Zn5和δ-NiZn8相层;但由于液相中含Fe,合金层外一定区域内有Γ2-Fe5Zn6Ni89粒子生成;Ni在不饱和Fe液相Zn中的溶解速率控制步骤与在纯液相Zn中相同,为界面反应和合金相层中的扩散速率所控制,而Ni在过饱和Fe液相Zn中溶解的主要控制机制是溶质Ni原子通过液相Zn中浓度边界层的扩散.说明液相Zn中所含的Fe加速了Ni的溶解.

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-Ni2Zn5 and δ-NiZn8phase layers; （2） some F2-FesZn6Ni89 particles may form in the liquid near the solid/liquid 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.