Potential of Metal-Matrix Composites as Superalloy Substitutes
NATIONAL PHYSICAL LAB TEDDINGTON (UNITED KINGDOM)
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The potential of metal-matrix composites as gas-turbine blade materials has largely been judged on the increased temperature capabilities they offer over the strongest current superalloys. However, several composites that have been rejected on this basis are either independent of or have low concentrations of critical alloying elements. Consequently they should be reassessed as reserve materials matching the performance of existing widely used superalloys that depend on strategically vulnerable constituents. A review of metal-matrix composites for high temperature applications will be made in order to identify materials that are insensitive to the supply of critical elements. An alternative approach might be to consider the potential of regenerating the original creep performance of certain monocarbide reinforced nickel based composites - such as Cotac 744 developed at ONERA - after service exposure. In this context the combination of perfectly elastic fibres in a creeping matrix would imply that high temperature deformation of these materials is almost completely recoverable.
- Laminates and Composite Materials