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本文对国内外关于高温合金铸件表面晶粒细化机理的几种观点作了验证;用X射线,显微镜和电子探针法对效果不同的型壳作了分析,发现铸件晶粒的细化与铝酸钴的分解以及合金中的活性元素有关;从浇铸后的型壳表面、铸件表面以及铝酸钴粉加不同活性元素的真空加热后的产物中均发现了Co(高温型)粒子。本文也做了铝酸钴加Al粉的真空差热分析并作了热力学计算,证明Co粒子的生成并不伴随着吸热,实际却是一个不大的放热效应。综合诸实验,作者认为铸件表面晶粒细化主要是由于Co粒子的核心作用;据此也探讨了合理的工艺,并巳用于工厂生产中,效果显著。
In this paper, several opinions on the mechanism of grain refinement on the surface of superalloy casting are validated. X-ray, microscopy and electron probe methods are used to analyze the effect of different types of shell. It is found that the grain refinement and The decomposition of cobalt aluminate and the active elements in the alloy; Co (high temperature type) particles are found from the surface of the cast shell, the surface of the casting and the cobalt aluminate powders plus different active elements after vacuum heating. In this paper, the differential thermal analysis of cobalt aluminate plus Al powder was also done and calculated thermodynamically. It was proved that the generation of Co particles was not accompanied by endothermic but in reality it was a small exothermic effect. Based on all the experiments, the author thinks that the grain refinement on the casting surface is mainly due to the core role of Co particles. Therefore, a reasonable process has also been explored and has been used in the factory production with remarkable results.