Effect of Neutron Irradiation at 4.5°K on Guinier-Preston Zone Formation in Aluminum-Zinc Alloys

The effect of fast neutron irradiation at 4.5°K on Guinier-Preston zone formation in the reverted as well as quenched alloys of Al-1.70 to 5.27 at.% Zn has been studied by means of electrical resistivity measurements. There is no indication of zone formation during irradiation nor during stage I and stage II of the isochronal annealing, but there is a large enhancement in the kinetics of zone formation during stage III annealing. The large increase in resistivity associated with zone formation begins at about 150° with the resistivity maximum occurring at about 260°K. Comparison with stage III recovery in pure aluminum suggests that vacancy migration, which controls Guinier-Preston zone formation in these alloys, results in stage III recovery in pure aluminum. In addition, there is an indication of solute-atom-vacancy binding and/or vacancy trapping by the zones since stage III extends to higher temperatures in the alloys than in pure aluminum.