Jadko M. The influence of alloying elements on the crystallization processes, structure and properties of copper condensates

The dissertation is devoted to the development of experimental technology and theoretical concepts of obtaining high strength thermally stable nanostructured copper-based metals. The structure of Cu-Ta, Cu-Mo, Cu-Co binary systems foils was investigated. Tantalum and molybdenum have been found to have a modifying effect on copper vacuum condensates refining its grain structure to sizes smaller than 100 nm. A physical model for the formation of grain boundary segregation of tantalum or molybdenum atoms and a mathematical relation that allows to estimate the required content of alloying elements to form a given grain size of a matrix metal are proposed. A higher value of the Hall-Petch coefficient in the two-component Cu-Mo and Cu-Ta condensates compared to single-component copper was experimentally observed and explained theoretically. It is established that the temperature of the beginning of the copper matrix grain growth depending on the type and content of the alloying element can reach 700-900ºC. It is shown that the stabilization of the grain structure during heating occurs through the formation of strong interatomic bonds between the segregating tantalum or molybdenum atoms and copper matrix atoms. Keywords: grain boundary segregation, grain size, vacuum condensation, thermal stability, nanostructure, strength, hardness, electrical conductivity.