Structure and properties of quasicrystalline and approximant EBPVD coatings of Al-based systems

This paper considers main features of the formation of Al-Cu-Fe and Al-Cr-Fe coatings with complex crystalline structures using high-rate electron beam physical vapour deposition (EBPVD). It is shown that the deposition of the coatings at substrate temperatures below approximately 570 K leads to the formation of nanostructured quasicrystalline or approximant phases. Mechanical behaviour at static and dynamic loadings of the coatings was investigated. It is established that the decreasing of the grain size in the materials to nanoscale values results in significant enhancement of their damping capacity (a mechanical energy dissipation in the materials) at alternate strains. Possibilities of the use of materials based on quasicrystalline and/or approximant phases as hard and high damping coatings for the prevention of early destruction of gas turbine blades are discussed.