Structure of vacuum Cu–Ta condensates

Abstract

The structure of vacuum condensate foils (separated from substrates) of the binary Cu–Ta system has been investigated both in the initial condensed state and after annealings at temperatures of up to 1000°С. It has been shown that the alloying of a vapor flow of the matrix metal (copper) with tantalum to ~0.5 at % makes it possible to reduce the grain size from 3 μm to 50 nm. Depending on the tantalum concentration, condensates exhibit a broad spectrum of structural states, i.e., single- and two-phase, a supersaturated solution of tantalum in the fcc lattice of copper, etc. The structure of the objects possesses a high thermal stability. The temperature of the start of grain growth in the copper matrix depends on the tantalum content and can reach 900°С. The dispersion of the structure of copper condensates and its thermal stability is due to the formation of segregates of tantalum atoms at the boundaries of grains of the copper matrix both in the process of condensation and upon subsequent annealing.