ZL108合金的快速凝固微观组织研究

Microstructure of Rapidly Solidified Eutectic ZL108 Aluminum Alloy

对采用单辊旋转淬冷法制备的ZL108合金进行了差示扫描量热分析(DSC)、X射线衍射分析(XRD)和透射电镜分析(TEM)。试验结果表明,在快速凝固合金的衍射谱中,只有Al的衍射峰出现,且具有比常规合金小的晶格常数。在DSC分析的热流-温度曲线上,合金开始熔化之前,快速凝固合金比常规合金多一个明显的放热峰。通过TEM分析得到,快速凝固ZL108合金具有无发达枝晶的亚共晶组织,由微米尺寸的晶粒和共晶区组成,共晶区中的Si颗粒达到了纳米尺寸。说明在快速凝固ZL108合金中,Si等合金元素已基本溶入Al的固溶体中,造成了溶解极限的增大和共晶点右移。

The microstructure of eutectic ZL108 aluminum alloy prepared by single roller rotating-quenching method was observed by DSC(differential scanning calorimetry), X-ray diffraction (XRD) and transmission electron microscope(TEM). The results indicate that the only presence of Al diffraction peak can be observed in the diffraction spectrum of the rapidly solidified alloy, exhibiting the samller lattice constant compared with the conventional alloy. And the rapidly solidified alloy has more an exothermic peak than the conventional alloy in the DSC curves of heat flow-temperature before melting. TEM observation reveals that there exists hypoeutectic solidified structure without developed dendrite in the rapidly solidified alloy, which is composed of micron grain and eutectic area in which nanometer Si particle exists. It can be concluded that the alloy elements such as Si has almost fully dissolved into Al solid solution, resulting in the enlargement of dissolvability and the movement towards right of eutectic point, meanwhile, the microstructure of the rapidly solidified alloy is greatly superior to that of conventional alloy.