Abstract
The paper is devoted to the study of the properties of silicides used as high-temperature materials of various designs. The surface energy and the thickness of the surface layer of atomically smooth metal silicides were investigated. To determine the surface energy, the dependence of the luminescence of metal silicide on the grain size of the phosphor was used. It was established that for binary silicides of a number of transition and rare-earth elements, the magnitude of the surface energy is in the range from 1 to 2 J/m2. It is shown that the calculated thickness of the surface layer d(I) does not exceed 3-6 nm (with the exception of four silicides). When the layer thickness exceeds d, a structural phase transition occurs. When the layer thickness d (II) ≈ 10d, size effects characteristic of nanostructures begin to appear. Classically as nanostructures are called objects which dimensions in one direction do not exceed 100 nm. Nanostructures classically are objects whiche dimensions in one direction do not exceed 100 nm. It has been established that for Cr5Si3 → V5Si3 → Ti5Si3 → Nb5Si3 silicides, the d(II) layer has dimensions from 106 to 131 nm, where size effects are detected. These silicides possess extraordinary physicomechanical properties and demonstrate a great potential of using them as high-temperature light materials for turbine blades, heat-shielding plates for combustion chambers and rocket nozzles.