粉末Ti-22Al-24Nb-0.5Mo合金热变形能力的对比研究

Powder metallurgy (PM) Ti2AlNb alloy of Ti-22Al-24Nb-0.5Mo (atomic fraction, %) was prepared from pre-alloyed powder using hot isostatic pressing (HIPing). Compression tests of PM Ti2AlNb alloy, heat treated PM Ti2AlNb alloy and wrought Ti2AlNb alloy with the same chemical composition were conducted on Gleeble-3800 testing machine. The testing temperatures were from 930oC to 1050oC, strain rates varied from 0.001 s-1 to 10 s-1, and engineering strain was about 50% for each compression. The results show that the deformability of PM Ti2AlNb alloy is comparable to that of wrought alloy, and heat treatment has no obvious effect on the hot workability of PM Ti2AlNb alloy. The high temperature flow behavior of Ti2AlNb alloys prepared by different fabrication routes is similar in this work, while processing windows for PM Ti2AlNb alloy is broader than casting alloys especially at low temperature or relative high strain rate. PM Ti2AlNb billets for hot deformation were prepared by a typical powder metallurgy process, and were upset or drawn out to different deformation in two-phase region. Macrostructure of deformed PM Ti2AlNb billets were observed, no macro crack was found in deformed PM Ti2AlNb billets and the deformation was uniform. The results of tensile tests show that the deformed PM Ti2AlNb alloy after heat treatment presents better tensile properties.