Diffusion of tin in copper-tin system solid solution

Abstract

Electron probe microanalysis (EPMA) was used to obtain concentration curves and calculate bulk diffusion coefficients in solid solutions of the copper-tin system in the tin concentration range of less than 13.9 wt.% (7.96 at.%) and temperature range of 500 to 650 ° С . Diffusion couples were made of pure copper (99,995 %) and two-component alloy obtained by direct alloying of metallic copper with chemically pure tin in Ar—H atmosphere at 1100 °C in the quartz reactor during 2 hours. Diffusion coefficients were calculated using the Matano-Boltzmann method and the method proposed by Grube, i.e. in the tin concentration range from 6 to 8 at.% ( D 1 ) on the top of the concentration curve, and from 2 at.% to zero ( D 2 ) on the bottom of the concentration curve. It is shown that tin diffusion coefficients in the concentrated solution were several times greater than in the diluted one. It is shown that diffusion activation energy values virtually coincide with isotope measurement data on tin diffusion in pure copper (187 kJ/mol). A qualitative interpretation is proposed for the tin diffusion acceleration effect in the concentrated solid solution of the copper-tin system.