EFFECT OF TERNARY ADDITIONS ON THE AGEING CHARACTERISTICS OF SOME ALUMINIUM - COPPER ALLOYS

Abstract

Effect of indium on the kinetics of pre-precipitation in Al-Cu alloys has been followed by measurements of electrical resistivity of quenched wires. The resistivity studies indicate that In has a marked effect on the pre-precipitation stage as it reduces the clustering rate to a large extent. , and. % for Al-Cu binary and Al-Cu-in ternary alloys are calculated and efforts made to correlate the effect of In addition in terms of high binding energy between an In atom and a vacancy. A simple analysis in terms of In/vacancy binding energy gives a value of 0,35 to 0.38 eV as compared to Cu vacancy binding energy of 0.10 eV. Hardness measurements carried out for Al-Cu binary alloys predicted the activation energy for the growth of 01 precipitate to be around 1.04 eV.