On the Aging Characteristics of Copper-2 wt% Beryllium Alloys with or without Additional Elements

Abstract

An investigation of the effects of quenching and aging temperatures and of additional elements on the aging characteristics of copper-2 wt% beryllium alloys has been carried out mainly by means of electrical resistance measurements. It has been found that appreciable clustering of solute atoms occurs during quenching and the rate of pre-precipitation during isothermal aging increases greatly with increasing quenching or aging temperature. It has also been observed that the increase in resistivity decreases with increasing aging temperature. The activation energy for the zone formation in the high purity binary alloy after quenching from 800°C is estimated to be 1.1 eV. The effect of additional elements on the zone formation process can be summarized as follows; magnesium and zinc accelerate zone formation, whereas cobalt and iron retard it. The results are interpreted in terms of a rather simple picture of the pre-precipitation phenomenon. The role of vacancy appears to be a fundamental one in determining the rate of zone formation. The variations of the maximum increase in resistivity against the various aging temperatures have been explained in terms of the variations of the number of zones formed. Other related problems such as the reversion and effects of additional elements are also discussed.