热镀锌用Zn-4Sb合金凝固组织的研究

Solidification Structure of Zn-4Sb Alloy Used for Hot Dip Galvanization

研究了锌花热镀锌用Zn-4Sb合金在4种不同冷却条件(炉冷、空冷、铁模水冷和铜板冷)下的凝固组织。结果表明,随着冷却速度减缓,先共晶的Zn-Sb金属间化合物粒子由片状转为块状,粒子的尺寸d与冷却速度c的关系近似符合d∝c-21;而共晶组织除粗化外,共晶中的Zn-Sb金属间化合物由规则的棒条状转变为不规则的块状。XRD结果表明,炉冷时合金相粒子为合金凝固后的金属间化合物ζ-Sb2Zn3相再经共析分解而生成的β-Sb3Zn4相,但在较快的冷速(水冷和空冷)下,亚稳态ζ相的共析分解可被抑制,铜板冷时ζ相的共析分解被完全抑制。

The effects of different cooling conditions, such as furnace cooling, air cooling, water cooling in Fe mould, copper plate cooling, on solidification of Zn-4Sb alloy used for hot dip galvanizing spangle have been observed. The results reveal that with the decrease of cooling rate, first eutectic Zn-Sb intermetallic compound particles are converted from laminar into bulk, in which the relationship between size of the particle and cooling rate is approximately accordant to empirical formula:d∝c-12. Meanwhile, the eutectic structure is coarsened and the Zn-Sb intermetallic compound in the eutectic structure is transformed from regular rod into irregular bulky. XRD analysis shows that in the condition of furnace cooling, the Zn-Sb intermetallic compound is β-Sb3Zn4 phase, which is the product of the ζ-Sb2Zn3 eutectoid decomposition, while the decomposition of metastable ζ phase can be restricted in the condition of water and air cooling, and it even totally be restricted in copper plate cooling.