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采用金相显微镜、扫描电镜、透射电镜和X射线衍射仪研究了冷却速率对Zn-30Al-1Cu合金微观组织的影响。结果表明,Zn-30Al-1Cu合金初始凝固组织主要由初生相α’相、包围在初生相周围的包晶β相和共析组织(α+η)组成,共析组织由包晶β相分解而来。凝固后期共析胞向枝晶中心生长,使α’相分解为层片α+η组织。随冷却速率增大,初生相由枝晶状变成等轴晶粒,尺寸也越来越小,沉积态晶粒尺寸最细小,铸态晶粒尺寸最大。冷却速率提高Cu元素在基体相中的固溶度,沉积态合金中没有发现富铜相ε,Cu元素全部固溶到基体中;普通铸造和快速凝固合金中均发现富铜相ε,它们存在于枝晶间和η相中。
The effects of cooling rate on the microstructure of Zn-30Al-1Cu alloy were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results show that the initial solidified microstructure of Zn-30Al-1Cu alloy consists mainly of α ’phase of primary phase, peritectic β phase and eutectoid structure (α + η) surrounding the primary phase. The eutectoid structure consists of β phase decomposition Come. In the late stage of solidification, eutectoid cells grow to the dendrite center, and the α ’phase is decomposed into the slice α + η tissues. As the cooling rate increases, the primary phase changes from dendritic to equiaxed grains, and the size becomes smaller and smaller. The grain size of the as-deposited grains is the smallest and the grain size of the as-cast grains is the largest. The cooling rate increases the solid solubility of Cu element in the matrix phase. No Cu-rich phase is found in the as-deposited alloy, and all the Cu elements are solid-soluted into the matrix. The copper-rich phase ε is found in ordinary cast and rapidly solidified alloys In the interdendritic and η phase.