On the design and feasibility of tantalum-base superalloys

• Published in: Journal of alloys and compounds Vol. 804; pp. 314 - 321
• Main Authors: Pickering, E.J., Christofidou, K.A., Stone, H.J., Jones, N.G.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05.10.2019; Elsevier BV
• Subjects: Air transportation; Alloy design; Alloy development; Alloy systems; Damage tolerance; Environmental impact; Gas turbine engines; Heat resistant alloys; High temperature; High temperature alloys; Nickel base alloys; Operating temperature; Phase identification; Precipitates; Refractory alloys; Superalloys; Tantalum; Tantalum alloys; Tantalum alloys; High temperature alloys; Refractory alloys; Phase identification; Superalloys; Alloy design
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.07.003

In order to reduce the environmental impact of air travel, it is desirable that the efficiencies of gas turbine engines are increased. One way to achieve this goal is to increase the operating temperatures of the engine cores. Unfortunately for aero-engine manufacturers, the temperature capability limits of the Ni-base superalloys used currently have been reached. Hence, new alloys need to be developed that are capable of operating at significantly higher temperatures. In this article, the potential of tantalum-base superalloys is discussed and explored. A suite of alloys based on the Ta-Al-Co system was investigated. It was found that an array of fine carbide precipitates was formed in the Ta-rich matrix in a subset of the alloys, which is promising in terms of developing a strong and damage-tolerant microstructure, but that the elemental partitioning of Al out of the matrix accompanying precipitation is likely to degrade environmental resistance. Nevertheless, it is believed that the design principles described have the potential to facilitate the development of the next generation of high-temperature alloys based on systems of this type. •A suite of Ta-Al-Co alloys are designed and investigated.•Aim to produce BCC (A2) matrix + A2-superlattice precipitates.•Fine Ta3Al2CoC precipitates in Ta-rich BCC matrix found after ageing.•precipitates had a consistent orientation relationship with the matrix