Microstructure and impression creep of age hardenable AA2219 Aluminium alloy modified by Sc, Mg and Zr additions

The present work pertains to impression creep of age hardenable AA2219 Aluminium-copper (6.3%) alloy correlated with microstructure with the addition of scandium, magnesium and zirconium. These additions were systematically varied by preparing alloys of different composition using gas tungsten arc melting. Impression creep technique was used to study the high temperature stability of the alloys. Modified compositions of the alloy resulted in fine equiaxed grains, refined eutectics, large number of high temperature stable and fine precipitates. Among all the compositions, 0.8%Sc+0.45%Mg+0.2 %Zr addition was found to be significant in improving the high temperature stability of AA2219 alloy. From the calculated values of stress exponent (n) and activation energy (Q), mechanisms of dislocation-climb and glide interaction with the precipitate particle are proposed. © 2010 TIIM, India.