The variation of work-hardening characteristics of Al-1 wt% Si and Al-1 wt % Si-0.1 wt% Zr-0.1 wt% Ti alloys

Al-1 wt% Si and Al-1 wt% Si-0.1 wt% Zr-0.1 wt% Ti alloys were used to trace the effect of Zr and Ti additions on the work-hardening characteristics. After solid solution treatment, specimens of both alloys were aged in the temperature range from 523 to 623 K and stress-strain tests were performed at room temperature. The coefficient of work-hardening, chi, the yield stress, sigmagamma, the fracture time, t(f), and the fracture stress, sigma(f), generally decrease with increasing aging temperature, while the total strain, et, and dislocations slip distance, L, increased, The results showed a sound stabilization effect of Zr and Ti on the aging characteristics of binary Al-1 wt% Si alloy. TEM investigations confirmed that the additions of Zr and Ti to Al-Si alloy retarded the coarsening kinetics of Si particles. The activation energies of the precipitation process involved were found to be 46 +/- 0.3 kJ/mole and 23 +/- 0.3 kJ/mol of the AI-Si and Al-Si-Zr-Ti alloys, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.