The influence of quenching rate on the kinetics of transformations of metastable phases in the Al-30 wt.% Zn alloy

Abstract

The effect of quenching rate on the precipitation process in the Al-30 wt. % Zn alloy has been studied by the X-ray diffraction and electron microscopy. No effect has been observed both on the T-T-T curve for the transformation of coherent into semicoherent phase and on the isothermal growth of precipitates of these phases. The significant dependence has been, however, found when the ageing of the investigated alloy led to the formation of incoherent phases. The T-T-T curves for α ^′_R and α ^′_R β transformations are shifted to the shorter ageing times with the increased quenching rate. The slopes of these T-T-T curves yielding parallel straight lines remain unchanged. The role of coherency stresses and of quenched-in strains in the investigated processes is discussed.