1991 Volume 31 Issue 8 Pages 931-937
Influences of hot deformation condition and alloy composition on the stress-strain relation, the workability and the microstructure have been studied in a temperature range between 1 200 and 1 600 K with strain rate of 10-4 to 10-1 sec-1, for binary intermetallics of Ti-4450 mol%Al melted by a plasma beam furnace. A peak stress due to dynamic recrystallization is observed in all stress-strain relations. The strain at the peak stress in the γ+α2 two phase alloys I smaller than that of the γ single phase alloy. The deformation stress and the deformability of these alloys are represented by a hot workability map with axes of temperature and strain rate. In the map, the area where the Ti-rich alloy can be hot worked soundly locates on the higher temperature range or the lower strain rate range compared with those of the γ single phase alloy. In the Ti-rich alloy with fully lamellar structure consisting of layers of the γ and α2 thin plates, it is difficult to obtain an uniform fine recrystallized structure because of stronger anisotropy in plasticity and much slower diffusion rate in comparison with the γ single phase alloy. In order to obtain the fine recrystallized structure, the alloy must be deformed repeatedly at a sufficiently high temperature over the (γ+α2)/(γ+α) eutectoid transformation temperature and with various direction of straining.
