Al基Al-Ag合金の降伏強度に対する時効の影響および低温歪時効効果

抄録

The time variation of the yield strength during ageing at various temperatures (after quenching from 550°C) and the effect of strain ageing at low temperatures on the flow stress have been studied with Al-Ag alloys containing 5∼20 wt.%Ag. The yield strength increases by 100°C ageing, and the increment is shown to be in a reasonable agreement with the value calculated from X-ray data on the basis of an idea of zone-hardening. No increase of the flow stress has been observed after strain aging at room temperature and at 100°C. Short-time annealing at intermediate temperatures (180∼200°C) brings about a decrease in yield stress which may correspond to the disappearance of zones. The yield stress reveals the maximum value upon the precipitation of the transient phase (γ′) and decreases as the γ′ phase grows to the stable γ phase, which may be associated with the variation of the stress field around precipitates during the growth of them. It is suggested that there may be a possibility of the nucleation of γ′-phase crystals in zones which will be promoted when there are some dislocation lines crossing them.