Microstructure and technological plasticity of cast intermetallic alloys on the basis of γ-TiAl

This work is devoted to the estimation of the technological plasticity of binary and alloyed γ titanium aluminides by conducting compression tests at T = 1000°C. The technological plasticity was shown to grow with decreasing size of grains and grain colonies and with increasing amount of ß-stabilizing elements in the alloys. The best technological properties are characteristic of the alloys that solidify completely through the ß phase, containing ß-stabilizing additions of niobium and molybdenum and microadditions of boron. These alloys are characterized by a small size of crystallites in the cast state; the use of special heat treatments makes it possible to substantially decrease the fraction of the lamellar component and to increase the content of the ß(B2) phase in them. For the most technological alloy, tensile tests in the cast state have been carried out. In the temperature range of T = 900-1100°C, superplastic elongations have been achieved.