P含量对Inconel 706合金凝固过程中(Laves+γ)共晶反应的影响

来源期刊：金属学报2010年第7期

论文作者：信昕 黄爱华 祁峰 张伟红 刘芳 杨洪才 孙文儒 胡壮麒

文章页码：873 - 878

关键词：Inconel 706合金； P含量； 凝固组织； 偏析

Key words：Inconel 706 alloy； P content； solidified microstructure； segregation

摘    要：研究了P对Inconel 706合金元素偏析和铸态组织的影响.结果表明,P在合金凝固过程中显著地偏聚于剩余液相中,并促进Nb和Ti等元素的偏聚,从而促进富Nb的Laves相和富Ti的η-Ni3Ti相析出;含0.004%P(质量分数)的Inconel 706合金枝晶间析出细小的(Laves+γ)共晶和少量针状η-Ni3Ti相;P含量超过0.016%以后,枝晶间析出块状Laves相,Laves相颗粒之间析出大量密集的η-Ni3Ti板条;此外,P含量由0.004%升高至0.016%,Laves相的初熔温度由1170-1180℃之间下降至1160-1170℃之间.分析认为,高度富集于剩余液相中的P强烈阻碍γ相的析出,因此,P含量增加使合金的终凝温度降低,而且导致合金的凝固结束反应由(Laves+γ)共晶转化为先析出富P的Laves相再析出γ基体的离异共晶反应.

Abstract: The effects of P on elemental segregation and as-cast microstructure in Inconel 706 alloy were investigated in this paper.The results showed that P was markedly enriched in residual liquid and enhanced the segregation of Nb and Ti,which promoted the precipitation of Nb-enriched Laves phase and Ti-enriched η-Ni₃Ti phase.In the as-cast alloy doped with 0.004% P (mass fraction),fine (Laves+γ) eutectic and needle likeηphase were formed in interdendritic region.As the P dopant was higher than 0.016%,blocky Laves phase was formed and lath η particles were precipitated among Laves particles.Moreover,with P increasing from 0.004% to 0.016%,the incipient melting-point was found to drop from 1170-1180℃to 1160-1170℃.In high P-doped alloys,the enrichment of P in the residual liquid was believed to hinder the solidification of 7 phase, as a result,the final solidification temperature was found to be decreased and the solidification was terminated by the solidification of γ phase prior to the formation of P-bearing Laves phase rather than forming the (Laves+γ) eutectic.