Tensile deformation mechanisms at different temperatures in the Ni-base superalloy GTD-111

The Ni-base superalloy GTD-111 is employed in high-power stationary gas turbines because of its high temperature strength and oxidation resistance. The temperature dependence of the tensile behavior of GTD-111 has been studied by tensile tests in the temperature range of 25–900 °C with a constant strain rate of 10−4 s−1. The results showed an abnormal tensile property variation with increasing temperature. The yield strength decreased slightly with temperature up to about 650 °C and then increased between 650 and 750 °C. Above 750 °C, a rapid decrease in the yield strength was found. The tensile strength showed a similar behavior except for its maximum that occurred at 650 °C. The elongation fluctuated more with temperature. TEM investigations have been performed on fractured specimens to evaluate the predominant deformation mechanisms at different temperatures. The TEM observations confirmed that these behaviors were affected by the γ′ properties and deformation mechanism change of GTD-111 at high temperatures.