Method for eliminating beta/B2 phase in casting high-Nb-TiAl alloy

The invention provides a method for eliminating a beta/B2 phase in a casting high-Nb-TiAl alloy, and belongs to the technical field of beta/B2 phase decomposition. The method comprises the following steps: placing an as-cast high-Nb-TiAl-based alloy containing the beta/B2 phase in a hot isostatic pressing furnace; applying pressure 150-200 MPa; heating to the temperature of 1,250-1,320 DEG C [namely the middle upper part of a (alpha+ gamma) two-phase region], insulating for 4-6 hours and then cooling in the furnace, and enabling the blocky beta/B2 phase at an alloy crystal boundary to obtain a fully lamellar structure or nearly lamellar structure. The method has the characteristics that a microscopic structure is regulated and controlled while compact ingot casting of the alloy by hot isostatic pressing is implemented, efficiency is high, and a blocky alpha2 phase is prevented from being formed at the crystal boundary in a process of eliminating the beta/B2 phase by common thermal treatment. The method is use