Taranenko V. Influence of metallic vacuum condensate microstructure on their dissipative properties

In the work investigation of the interrelation of micro- and substructure characteristics and mechanical properties of materials under their static and dynamic loading is performed in the case of vacuum condensates of FCC-metals (copper, nickel) and BCC-iron. It is shown for the first time that dissipative properties of these metals are determined not only by grain size, but also by the type and size of characteristic substructural elements: for nanostructured metals, in particular, those with polydomain structure, mechanical energy dissipation characteristics differ qualitatively from the respective characteristics of its dissipation by coarse-grained (monodomain) metals with dislocation substructure. This is manifested in the change of the type of curves of amplitude dependence of logarithmic damping decrement (LDD) from parabolic to gently rising linear dependence, as well as in uniform increase of LDD values in a broad range of deformation amplitudes at condensate heating and their resistance to cycling loads. Increase of metals damping level at reduction of the size of characteristic elements in their microstructure is accompanied by increase of metal strength. Such a combination of strength and high damping capacity (DC) in nanostructured metals is due to the scale factor and thermally activated processes of atomic rearrangement on grain and subgrain boundaries. This was the basis for substantiation of the possibility of creating hard high-damping materials based on nanocomposites, which combine high hardness and high DC. Fatigue fracture resistance of titanium substrates with coatings based on nanostructured materials was studied at alternating strains. A bilayer coating structure for thin-walled titanium parts (GTE compressor blades) was proposed for the first time. This coating consists of a lower layer (bond coat) based on nanotwinned copper and outer hard layer based on high-damping Al-Cr-Fe alloy, and ensures a high surface hardness of the blades and high DC, without violating the fatigue fracture resistance of the blade under cyclic deformation.