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ULTMAT
Ultra High Temperature Materials for Turbines

Background

Increasing the temperature capability of turbine blade materials has been identified as a major requirement to develop efficient and clean aircraft. For high-pressure turbine components, the development of new alloys offering increases in metal surface temperatures of as much as 150°C over the presently used Ni-base, single-crystal superalloys is of strategic importance.

Project objectives

The project aims to provide a sound technological basis for the introduction of innovative materials, namely Mo- and Nb-based Silicide multiphase alloys, which have enhanced high temperature capabilities of up to 1 300°C, compared to the presently used Ni-base single-crystal superalloys, for application in aircraft/rotorcraft engines and in aero-derivative land-based gas turbines. The objectives of the project are:

  • the definition of new alloy compositions with an acceptable balance of mechanical properties and oxidation resistance
  • the development of cost-effective processing technologies
  • the design of coating systems to improve oxidation resistance
  • the creation of a properties database, which will provide data for applications under specific turbine service conditions
  • a preliminary assessment of the implementation conditions of the materials in turbines (machining, joining, etc.).
Aero-engine hot section turbine blade (height: about 10 cm)
Aero-engine hot section turbine blade (height: about 10 cm)

Description of the work

The work plan has been constructed as a fast-track programme with simultaneous efforts on all technological aspects leading to representative tests, as well as technical/economic validation:

  • alloy composition development with respect to specified property requirements;
  • development of cost-effective and reliable processing technologies for both Nb- and Mo-based Silicide alloys. The composition and microstructural control of the multiphase alloys is of prime importance to enhance the current state-of-the-art. Therefore, a range of processes provided by the consortium (including arc-melting, ingot casting, powder-metallurgy processing, thermo-mechanical processing, etc.) together with the expertise in inter-metallic and refractory metal alloy development, will be used extensively for alloy composition screening and improvement up to the manufacturing of a prototype blade;
  • development of adequate oxidation protection coatings;
  • characterisation of the most relevant alloy properties (mechanical: high temperature yield strength and creep resistance, fracture toughness; physical, thermal, etc.);
  • development of fabrication technologies.

Expected results

The expected result of the project is a thorough evaluation of the capability of refractory metals, Nb- and Mo-based Silicide multiphase materials , to withstand future increased temperature turbine service conditions, relying on mechanical, microstructural and environmental investigations in close relation to industrial-scale material processing and component fabrication technologies.

Microstructure of an arc melted Nb-silicide based alloy. Light grey: silicide dendrites
Microstructure of an arc melted Nb-silicide based alloy. Light grey: silicide dendrites

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