真空悬浮熔炼高铌TiAl合金铸锭的成分组织均匀性

Homogeneity of Composition and Structure for High Nb Containing TiAl Alloy Ingots Prepared by Vacuum Levitation Melting

摘要:

从宏观缺陷、化学成分分布、O含量和微观组织等几个方面，分析了真空悬浮熔炼制备高铌TiAl合金铸锭的冶金质量。结果表明，经过合理设计锭模可以获得集中缩孔面积小、无裂纹的铸锭。真空悬浮二次熔炼获得的铸锭不同部位有成分>1at%的Al宏观偏析；采用优质原料，通过抽真空→熔化→充氩气→精炼的工艺路线可以使合金的含氧量达300 μg/g。虽然存在Al宏观偏析，但是不存在原料未熔和在铸锭局部富集的现象，铸锭组织为近片层组织。

Abstract:

Metallurgical quality of high Nb containing TiAl ingots prepared by vacuum levitation melting (VLM) has been investigated from respects of macroscopic defects, composition distribution, oxygen content and microstructure. After twice melting and pouring the melting into properly designed mould, crack-free ingots with small shrinkage defects could be obtained. There are Al macrosegregation (>1at%) at different positions of ingots. Oxygen content is decreased to 300 mg/kg by using high quality raw materials and a optimized melting process. There are not phases and microstructures induced by high melting point raw materials in the ingot, and the as-cast microstructures of the ingots are typically nearly lamellar microstructure.