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

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.