A study of age-hardening of Al–3.85% Cu by the divergent X-ray beam method

A1-3.85% Cu single crystals were studied by means of the back-reflection divergent X-ray beam method after solution treatment, various modes of quenching and various stages of age-hardening. A complete strain analysis was developed by which the principal strains in a crystal or polycrystalline material can be determined provided the changes of d-spacings of more than six independent (hkl) reflections are recorded. The analysis applied to the various stages of age-hardening of crystals subjected to a fast quench after solution treatment disclosed an anisotropy of strain distribution in the matrix. The maximum strain corresponding to the ageing stage associated with the formation of G. P. zones coincided with one of the [100] directions and shifted about 20 when the 0' phase was predominant. The anisotropy of strain distribution was interpreted in terms of a preferred vacancy migration due to thermal and concentration gradients introduced by quenching.