Fesiun O. Regularities formation of nanosized substructure of FCC-metals during vacuum deposition and its effect on the mechanical properties

The thesis is devoted to the study of the micro- and substructure of the condensates of FCC-metals obtained by electron beam deposition from vapour phase. Effect of deposition parameters (substrate temperature, rate deposition), stacking fault energy and insoluble impurities on the condensate substructure are investigated. It is shown that there is a critical temperature above 0.45 Tm, where Tm - melting temperature of metal, above and below which mono-domain grain structure and poly-domain grain substructure are formed, correspondingly. The type of poly-domain grain substructure is determined by the stacking fault energy of metal: for small stacking fault energy (less than 100 mJ/m2) - nanotwinned substructure, for high stacking fault energy (more than 100 mJ/m2) - nanofragmented substructure. It is found that nanotwinned substructure is formed if the crystallites grow in the crystallographic direction <111>. It is shown that deacreasing substrate temperature, increasing rate deposition, reducing stacking fault energy and at introduction insoluble impurities in the condensates lead to decreasing the thickness of twin domains. It is observed that hardness of the condensates with nanosized substructure is several taimes higher as compared to that of the condensates with mono-domain graines. It is revealed that dissipative properties of the vacuum condensates is manifested in a significant weakening of amplitude dependence of damping level and enhancment of temperature influence on it. Change of mechanical properties of vacuum condensates is associated with influence of nanosized substructure on its.