High temperature creep behaviour of gamma-titanium aluminides (gamma-TiAl)

Abdallah, Zak; Dixon, M; Whittaker, M; Bache, M

Abstract

Compared to conventional titanium alloys, gamma titanium aluminides (gamma-TiAl)offer highly desirable properties to the design engineer, with relatively high specific stiffness and high temperature capability. However, a significant drawback of this class of material is the low ductility at room temperature under monotonic tensile loading, which only marginally improves at elevated temperatures. Although care is clearly required in implementing these materials, the property improvements which can be made over existing gas turbine alloys provide the incentive for further research. A comprehensive creep evaluation has been undertaken to investigate the time dependent properties of a gamma-TiAl (Ti-45Al-2Mn-2Nb) at elevated temperatures. When compared to an established high temperature titanium alloy, Ti834, significant improvements in creeplife were demonstrated for equivalent stress conditions. This was explained by a superior resistance to surface oxidation in the gamma-TiAl, with notable alpha case formation prevalent in Ti834 leading to brittle surface cracking and therefore premature failure at temperatures in excess of 625⁰C. Under creep conditions, good ductility was measured in the gamma-TiAl, with values consistently exceeding 15% under the combinations of stress and temperature employed.

• Presentation Conference Type: Conference Paper (unpublished)
• Conference Name: The 12th International Conference on Creep and Fracture of Engineering Materials and Structure
• Start Date: Jul 3, 2012
• Deposit Date: Jul 12, 2023
• Public URL: https://uwe-repository.worktribe.com/output/10932398