Effect Of Heating Rate On Recrystallization Behavior And Microstructure Of Ultra-high Purity Al-0.5%Cu Alloy

Ultra-high purity sputtering target material Al-0.5% Cu was widely used in electronics industry. In this paper, different annealing systems were used to improve the microstructure of Al-0.5% Cu alloy so as to optimize the performance of this sputtering target. A ultra-high purity Al-0.5%Cu plate was cold rolled to 90% thickness reduction and consequently annealed at various temperatures ranged from 200 ℃ to 300℃ for different holding time(2.5-80min) by slow heating rate and rapid heating rate. The effect of heating rate on recrystallization behavior and microstructure of Al-0.5%Cu were investigated using electron channeling contrast(ECC), electron backscatter diffraction(EBSD), X-ray diffraction(XRD) and Vickers hardness testing. These following conclusions were drawn from this research:① The recrystallization temperature for rapid heating rate annealing was 225℃,which was 250℃ for slow heating rate. Rapid heating rate annealing can lower the recrystallization temperature of high purity Al-0.5%Cu, prompting earlier recrystallization. Under the condition of same temperature, rapid heating rate annealing needed shorter time to complete recrystallization.② The recrystallization microstructure and texture were greatly influenced by the annealing heating rate. The rapidly heated sample was comprised of almost equiaxed grains with a more uniform size(18.6 ± 13.7μm), while the slowly heated sample was comprised of elongated grains with a high length/width ratio(23.7±17.5μm). In the case of slow heating rate annealing, the texture mainly consisted of Cube ND(4.0%) and P texture(5.7%), while the texture was characterized by a weaker Cube(5.0%), and a perfectly random texture(70.3%) in the case of rapid heating rate.③ The activation energy for slow heating rate was 81.31 KJ/mol and rapid heating rate was 64.26 KJ/mol,rapid heating rate lower the activation energy for high purity Al-0.5%Cu.