On the Design and Feasibility of Tantalum-Base Superalloys

In order to reduce the environmental impact of air travel, it is desirable that the
eciencies 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 signicantly 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 ne 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.