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用稀士熔盐电解法及熔盐直接反应法对Al-Si液态共晶合金分别定量添加了La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Ho,Er和Y共十一个单一稀土以及一个混合稀土的变质剂。通过显微结构分析系统地研究了在70—80℃/min冷却速度下合金的变质效果。发现Eu,(Yb)具有最强的变质能力,La次之,并发现其均为“长效”变质剂.Ce,Pr,Nb及混合稀土的变质能力稍低于La。稀土元素的变质能力随原子半径的减小而迅速降低.Sm以下已减弱至微不足道的程度。Eu和(Yb)的变质能力主要是与其原子半径的突跃增大有关。Er,Y不具变质能力。根据Eu和Ac原子半径的接近以及Y-La-Ac的同族规律,推测Ac将具有还要大的变质效果。据此总结了强变质剂Na,Sr,Ac在元素周期表中的斜线位置,认为变质剂元素的变质能力主要取决于其价电荷数,原子半径和原子序数的一定组合。
The total amount of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er and Y in the Al-Si liquid eutectic alloy were quantitatively determined by the method of rare earth molten salt electrolysis and molten salt direct reaction A single rare earth and a mixed rare earth modifier. The microstructure analysis systematically studied the effect of modification of the alloy at the cooling rate of 70-80 ℃ / min. It is found that Eu (Yb) has the strongest metamorphism and La is the second, and both are found to be “long-lasting” metamorphic agents. The metamorphism of Ce, Pr, Nb and mixed rare earths is slightly lower than that of La. The metamorphism of rare earth elements decreases rapidly with decreasing atomic radius, and the sub-Sm has weakened to negligible levels. The metamorphism of Eu and (Yb) is mainly related to the increase of their atomic radius. Er, Y is not metamorphic. According to the closeness of Eu and Ac atomic radius and the same law of Y-La-Ac, it is speculated that Ac will have even larger metamorphism. Based on this, we summarize the positions of the strong modification agents Na, Sr and Ac in the periodic table of the periodic table. It is concluded that the metamorphic agent’s metamorphism depends mainly on its valence number, atomic radius and atomic number.