TiAl 基合金固相焊接界面及其显微组织分析

SOLID PHASE WELDING AND MICROSTRUCTURE ANALYSIS OF TiAl BASED ALLOY

采用惰性气氛下热压方法，研究了Ｔｉ－３３Ａｌ－３Ｃｒ（质量分数，％）合金粗大（α２／γ）层片组织材料／粗大（α２／γ）层片组织材料及粗大（α２／γ）层片组织材料／细小双态组织（γ＋α２／γ）材料焊接界面及其显微组织，以及随后的热处理退火制度对此界面的影响．试验结果表明，粗大（α２／γ）／粗大（α２／γ）界面的显微组织特征受界面粗大层片状晶团位向的影响．此类界面经过１２５０℃退火，其显微组织变化不明显，但促使γ相等轴晶退火孪晶的形成；而经过１２８０℃退火，原焊接联接界面变宽，在（α２／γ）晶团界面上发生部分再结晶现象；而经过１３５０℃退火（Ｔｉ－３３Ａｌ－３Ｃｒ合金的ｔα≈１３０５℃），整个联接件材料发生重结晶，形成新的、粗大的全层片状组织，原焊接联接界面消失．采用细晶双态组织材料与粗大全层片状组织材料对焊，可得到良好的固态焊接结合面．

Through hot pressing in Ar atmosphere,the joining interfaces and their microstructures of coarse( α 2/γ ) lamellar material/coarse( α 2/γ ) lamellar material and coarse( α 2/γ ) lamellar material/fine duplex( γ+α 2/γ ) material have been studied and the subsequent heat treatment has also been studied.Results show that coarse( α 2/γ )/coarse( α 2/γ ) interface and its microstructure characteristics are affected by the orientations of coarse( α 2/γ ) along the interface.After annealing at 1250 ℃,the microstructure in the interface had little variation except for the formation of γ equiaxial annealing twins; after annealing at 1280 ℃,the interface was widened,and recrystallization occured in the boundaries of ( α 2/γ ) colonies; after annealing at 1350 ℃,recrystallization occured on the whole joined material,new coarse fully lamellar microstructure formed and the original joining interface disappeared.Perfect joining interface can be obtained through joining of the duplex material with coarse fully lamellar material.