STABILIZATION EFFECT OF ZR AND TI ADDITIONS ON THE AGING CHARACTERISTICS OF AL-1 WT-PERCENT SI ALLOY THROUGH A CREEP STUDY

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 behaviour of the steady state creep. After solid solution treatment specimens of both alloys were aged at 623, 673, 723 and 773 K and creep tests were performed at room temperature by applying stresses of 60.0, 62.4, 64.7 and 67.1 MP a. The results showed a sound stabilization effect of Zr and Ti on the ageing characterstics of binary Al-1 wt% Si alloy. Values of the appl ied stress sensitivity parameter, mi obtained were in the range of (20 -34) for Al-Si ahoy and (14-19) for Al-Si-Zr-Ti alloy. Time to rupture was found to be strongly increased by Zr and Ti additions. The activa tion energies of the precipitation process involved were found to be 8 1.9 kJ/mole and 33.7 kJ/mole of the Al-Si and Al-Si-Zr-Ti alloys respe ctively.