The internal-variable theory of inelastic deformation, and the dynamic-materials model, were used to interpret high-temperature deformation mechanisms. Load-relaxation and tensile tests were performed on fine-grained duplex γ-TiAl at 800 to 1050C. The results

of the load-relaxation tests, where deformation took place at an infinitesimal level (0.05), showed that the deformation behavior was well-described by a sum of dislocation-glide and dislocation-climb processes. Processing maps were constructed by performing compression tests at 800 to 1250C, using strain rates ranging from 10 to 10-4/s. Two domains were identified in processing maps obtained at finite strain levels (0.2, 0.6). One domain was found in the region of 980C and 10-3/s; with a peak efficiency (maximum efficiency of power dissipation) of 48% and was associated with dynamic recrystallization. Another domain, with a peak efficiency of 64%, was located in the region of 1250C and 10-4/s and was attributed to superplasticity.

High-Temperature Deformation Behavior of a Gamma TiAl Alloy. Microstructural Evolution and Mechanisms. J.H.Kim, T.K.Ha, Y.W.Chang, C.S.Lee: Metallurgical and Materials Transactions A, 2003, 34[10], 2165-76