Faults in Co3(Al,W) precipitates that form during high temperature deformation.

New Co-Base High Temperature Alloys

New structural and functional materials enable a multiplicity of paths to improved efficiency in energy generation, storage, transmission and conversion. While alternative energy technologies are highly desirable, for the foreseeable future fossil fuels will be a primary energy source. This motivates discovery of new structural materials that can increase the operating temperatures within energy generation systems and provide critically needed improvements in the efficiency of power generation.

The discovery of a stable ternary Co3(Al, W) intermetallic compound with an ordered L12 structure has provided a pathway for development of a new class of load-bearing cobalt-base high temperature alloys. The thermodynamic coexistence of the γ -Co solid-solution phase with fcc structure and the γ ' - Co3(Al, W) phase and the similarity of their lattice parameters permit establishment of a two-phase structure with a high degree of coherency. This structure consists of submicron regularly aligned cuboidal γ ' precipitates embedded in a continuous γ matrix phase. This structure is morphologically identical to the microstructure of Ni-base superalloys. Our recent research on ternary and quaternary variants of these two-phase L12-containing systems indicates a potential temperature benefit of up to 150˚C relative to current nickel-base alloys. This translates to a very substantial benefit in energy efficiency for advanced turbine systems. To achieve these benefits, a broader range of composition space must be explored in an efficient manner to optimize properties and concurrently identify compatible environmental and thermal barrier coating systems.

Researchers

Tresa Pollock

Research interests include the mechanical and environmental performance of materials in extreme environments, unique high temperature materials processing paths, ultrafast laser-material interactions, alloy design and 3-D materials characterization.

Jean-Charles Stinville

  • Deformation behavior and damage of polycrystalline and monocrystalline materials in relation with microstructure and/or microstructure evolution induced by heat/conversion treatment
  • Effect of microstructure and mechanical properties changes on deformation behavior and damage of metallic materials
Marie Agathe Charpagne

Marie-Agathe Charpagne

https://www.researchgate.net/profile/Marie_Agathe_Charpagne

Colin Stewart

Colin now explores the oxidation behavior of novel L12 cobalt-based alloys for turbine applications. His work requires a solid understanding of thermodynamics and kinetics, as well as a variety of characterization techniques including Raman / Photo-Stimulated Luminescence Spectroscopy, SEM, XRD, TEM, and EDS.