含氮TiAl合金热处理过程中的组织演化

Microstructure Evolution of Nitrogen Containing TiAl Alloy During Heat Treatment

高Nb-TiAl合金是因其具有高强度和比模量,良好的高温抗氧化性、蠕变抗力等优点,在航空航天、汽车工业都有较好的应用前景。根据合金特点,TiAl合金的合金化研究一直是研究的热点方向之一。通过对Ti-46Al-8Nb-2.5N进行不同时间的热处理,研究热处理工艺对合金显微组织演化的影响规律。研究表明,超过固溶限度后,氮元素将以氮化物的形式析出,其形成的氮化物为Ti2AlN。同时发现,热处理时间增长,合金的片层组织有粗化现象,且析出物Ti2AlN聚集现象十分显著。同时,在组织中发生相变,析出新相Ti3AlN相。

High Nb containing Ti Al alloys are very promising in the aerospace and automotive industries because of their high strength and specific modulus,better high temperature oxidation resistance,creep resistance.Meanwhile,the alloying study of Ti Al alloys according to the alloy characteristics has been one of the hot research directions.The effect of heat treatment on the microstructure evolution is investigated by heat treatment of Ti-46Al-8Nb-2.5N at different times.It is shown that when the nitrogen content exceeds the solid solution limit,it will precipitate in the form of nitride Ti2Al N.With the increase of heat treatment time,the lamellar clusters of the alloy organization have a gradual coarsening phenomenon,and the aggregation of precipitates Ti2Al N is very significant.At the same time,phase transformation occurs in the microstructure,and a new phase Ti3Al N phase is precipitated.