定向凝固过程中Ti-47Al-2Cr-2Nb合金与Y₂O₃陶瓷的相互作用

来源期刊：金属学报2010年第7期

论文作者：张花蕊 高明 唐晓霞 张虎

文章页码：890 - 896

关键词：TiAl合金； Y₂O₃； 定向凝固； Y₂O₃/Al₂O₃双层陶瓷管

Key words：TiAl alloy； Y₂O₃； directional solidification； Y₂O₃/Al₂O₃ double layers ceramic tube

摘    要：本文研究了定向凝固条件下Ti-47Al-2Cr-2Nb合金与Y₂O₃/Al₂O₃双层结构陶瓷管内层Y₂O₃的相互作用.结果表明,Y₂O₃层有效地阻隔了化学稳定性较差的Al₂O₃外层与TiAl合金熔体的接触,从而避免了Al₂O₃与TiAl之间的化学反应.合金铸棒内含有平均体积分数约为0.14%的少量Y₂O₃夹杂物,主要是由于在定向凝固实验初期阶段Y₂O₃陶瓷在受到流动的合金熔体渗透侵蚀后脱落所致,对持续时间不敏感.高温下合金熔体促进了Y₂O₃陶瓷表层的再烧结并形成了2-10μm致密的阻挡层,从而阻止了合金熔体向Y₂O₃陶瓷内部的进一步渗透以及内部未完全烧结Y₂O₃陶瓷颗粒向合金熔体中的继续脱落.

Abstract: Interaction between Ti-47Al-2Cr-2Nb alloy and inner layer Y₂O₃ of Y₂O₃/A1₂O₃ double-layer ceramic tube has been investigated during directional solidification.The results show that the Y₂O₃ layer effectively prevents the chemical reactions between TiAl alloy melt and exterior layer Al₂O₃ with lower chemical stability by blocking their direct contact.The DS alloy ingot contains Y₂O₃ inclusions which mainly come from the shedding of Y₂O₃ from ceramic tube inwall by being penetrated and eroded by fluid alloy melt in the initial phase of the directional solidification test.The average volume fraction of the inclusions is only about 0.14% and is insensitive to time.The re-sintering of the Y₂O₃ ceramic surface layer occurs and a 2-10μm dense barrier layer is formed by dint of alloy melt at high temperature.It prevents further pervasion of alloy melt into the Y₂O₃ ceramic and shedding of imperfectly sintered Y₂O₃ particles into the alloy melt.