微量稀土Ce对金合金铸态组织及其硬度的影响

文中研究了微量稀土元素Ce在金合金中的分布情况,观察了稀土元素Ce不同添加量对金合金铸态组织及其硬度的影响.研究发现:在添加Ce的金合金中,Ce部分固溶,部分作为异质点Ce-Si化合物存在,基本没有Ce的偏聚;添加0.075?金合金铸态组织就可以达到较好的晶粒细化效果,分析其作用机理是添加Ce的金合金以高熔点的Ce-Si化合物和氧化物作为异质点,起到异质晶核的作用而细化组织;在低于Ce的金合金固溶度时,铸态合金的硬度随Ce含量增加而升高,过量Ce对金合金的铸态硬度影响不大;利用时效处理,能显著地提高金合金的硬度,Ce主要强化机制在于固溶强化.

Effects of trace rare earth Ce on as-cast microstructure and hardness of gold alloy

In this paper,the distribution of trace rare earth element Ce in gold alloy,effects of rare earth Ce on as-cast microstructure and hardness of gold alloy with different additives are studied.The results show that: in gold alloys,part of Ce forms Ce-Si alloys with silicon and the rest of Ce solute in the base uniformly.Gold alloys as-cast structure generally can be refined after adding 0.075% rare earth Ce.The dominant refining mechanism of Ce is that Ce can combine with silicon and oxygen to form high melting-point compounds,used as heterogeneity crystal nucleus and metamorphism.When Ce contents below the solid solubilities of Ce in Au,the hardness of cast gold alloy increases with the increasing of Ce content,but excessive Ce places little effect. In addition,the use of aging treatment,can also significantly improve the hardness of the gold alloy.The main strengthen mechanism of Ce is the solid-solution strengthening.