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对液态金属停止流动机理的研究工作,许多铸造学者各有自己的理论基础和实验依据,其中著名的是美国M.C.Flemings的学说。M.C.Flemings的试验以铝锡合金作为研究对象,提出了极纯金属,低浓度溶质组元合金和高浓度溶质组元合金三种合金停止流动机理的模型,认为前二种合金是由于流股中部柱状晶生长形成堵塞而停止流动的,只有高浓度溶质组元合金才是由于流股前沿固相质点的堵塞而停止流动的。这是两种完全不同的金属停止流动的方式,但它们之间是如何过渡的,至今未见到实验报导和理论分析。为了研究清楚这个问题,作者进行了一系列的实验,所采用的试验用铝合金的含硅量都不大于0.4％。这些合金不仅属于稀释合金范畴。而且还可看作工业纯的金属。从实验结果的分析中可见,随着铝合金中含硅量的增加,流股端部固相质点的积聚便一直发展。Al—Si稀释合金因冷却而停止流动是从流股中部柱状晶堵塞演变到流股端部等轴晶堵塞。根据传热学和金属凝固学的原理,结合分析前人和本文中的实验结果,文中提出了一般工业用铸造合金停止流动的通用模型.M.C.Flemings提出的金属凝固停止流动的两种凝固模型是此通用模型的特例。
Many scholars of foundry have their own theoretical basis and experimental basis for the research on the mechanism of liquid metal to stop the flow, of which the famous is the theory of M.C. Flemings in the United States. The experiment of MCFlemings took aluminum-tin alloy as the research object and put forward a model of stopping the flow mechanism of the three alloys of very pure metal, low-concentration solute elemental alloy and high-concentration solute elemental alloy. It is considered that the first two kinds of alloy are due to the central part Columnar crystal growth to form a blockage and stop the flow, only the high concentration of solute elemental alloy is due to the front of the flow blockage of the solid particles stop flowing. There are two completely different ways in which metals stop flowing, but how they transition between them has so far not been reported experimentally and theoretically. In order to study clearly this problem, the author conducted a series of experiments, the experimental use of silicon aluminum content of not more than 0.4%. These alloys not only belong to the category of diluted alloy. But also as industrial pure metal. From the analysis of the experimental results, it can be seen that with the increase of silicon content in the aluminum alloy, the accumulation of solid-phase particles at the end of the stream has been progressing. The flow of Al-Si diluted alloy due to cooling ceases from blockage of columnar crystals in the middle of the stream to blockage of equiaxed grains at the end of the stream. According to the principle of heat transfer and metal coagulation, combining with the analysis of the predecessors and the experimental results in this paper, a general model for stopping the flow of general industrial cast alloys is proposed.The two solidification models proposed by MCFlemings to stop the flow of metal solidification are A special case of this universal model.