用自射线照相、电子探针及离子探针等方法研究了铈球铁、轻稀土-镁球铁、钇基重稀土球铁、钇基重稀土-镁球铁中铈、钇、镁、钙等球化元素以及硫的分布。自射线照相所获得的乳胶干板各处的黑度分布近似地反映了石墨与基体中放射性物质的重量百分浓度。在金相显微镜和扫描电子显微镜观察中均发现,有的球墨有核心。电子探针的探测结果说明:在铈球铁中,有的球墨的核心为硫化铈;在用铈、钙稀土合金处理的球铁中,有的球墨的核心有硫化铈和硫化钙;在轻稀土-镁球铁中,有的球墨的核心有铈、镁、硅的化合物。 球化元素铈、镁、钇、钙等和反球化元素硫在球墨中的分布是多样的;这些元素的化合物可能构成某些球墨的结晶核心;有的球墨边缘或周围有铈、钇、镁、钙的富集;有的球墨中铈为均匀分布,钇为不规则分布;在相当多的球墨中,没有铈、钇等球化元素的富集。根据球化元素的多种分布形态,认为球墨的成因,也不限于一种。球化剂的主要作用可能是它能去除硫、氧等杂质,改变了馆体的表面张力和熔体-石墨间的界面张力,从而有利于球墨的形成。 对双层球墨的成因进行了初步分析。
The distribution of nodularizing elements such as cerium, yttrium, magnesiumor calcium and of subversive such as sulphur in R. E. treated spheroidal graphitecast irons has been studied by means of autoradiograph, electron probe and ionmass microanalysis. The blackness of autoradiography to a first approximationshowed the content of the radioactive components in graphite and in matrix. Cer-tain graphite spherulites each contained a nucleus, the composition of which wasdifferent with different nodularizing elements. The distribution of the different nod-ularizing elements cerium, magnesium, yttrium, calcium and the subversive agentsulphur in nodular cast iron occurred in many different ways, compounds ofnodularizing elements might exist as nuclei of graphite spherulites with yttrium,magnesium and calcium etc. around them. In certain spherulites, cerium was found-to distribute uniformly but yttrium irregularly. In cast irons treated separately bycerium, yttrium or other nodularizing elements, however, hardly any rare earthwas found to enrich around most of the spherulites. In view of the complex be-havior in rare earth distribution, it would appear that graphite spherulites are form-ed far from only in a single way. The interaction due to the nodularizingelements in fact may be the result of scavenging subversives (sulphur, oxygen, etc.),in its consequence the surface tension of melt and the interfacial tension at themelt-graphite boundaries thus facilitating the formation of graphite spherulites.The mechanism of duplex graphite spherulites formation has also been primarilyexamined.
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