低温预形变热处理对铸造Ti-48Al-2Cr-2Nb合金显微组织的影响OA

TiAl alloys possess advantages such as low density,excellent high-temperature oxidation resistance,and comprehensive high-temperature mechanical properties,making them highly regarded as lightweight high-temperature structural materials in the aerospace industry.However,the inherent brittleness of TiAl alloys at room temperature severely limits their potential for engineering applications.Consequently,improving the microstructural uniformity and grain refinement has become a research focus for TiAl alloys.The influence of deformation heat treatment parameters on microstructural evolution in cast Ti-48Al-2Cr-2Nb alloys was investigated by employing a combination of low-temperature pre-deformation and subsequent heat treatment.Additionally,in situ observations using high-temperature laser scanning confocal microscopy were employed to analyse phenomena such as recrystallization,grain growth,and lamellar precipitation in the low-temperature deformed microstructure.Starting from an initial coarse microstructure of the as-cast alloy with lamellar colonies of approximately 400 μm,fine-grained duplex microstructures with lamellar colonies and γ grain sizes of 21 and 12 μm can be obtained through scientifically controlled low-temperature pre-deformation above the ductile-to-brittle transition temperature and subsequent heat treatment in the α+γ phase region.