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

Abstract

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.

Elastic-strain tensor by Rietveld refinement of diffraction measurements

“…can be solved simultaneously to yield the strain components in the specimen coordinate system. 16,18 The strain tensor is symmetric, so it has six independent components, and measurements for at least six independent specimen positions are required. It is advantageous, however, to collect data at as many specimen orientations as feasible.…”

Generalised Least-squares Determination of Triaxial Stress States by X-ray Diffraction and the Associated Errors

“…Measuring strains in six independent directions is therefore sufficient to determine the strains Eij (Nye 1976). The accuracy may be improved by measuring more than six strains ec/>l\I and determining the strains Eij by a least-squares procedure (Imura et al 1962). …”

Design of a new Kossel pattern generator

“…Thi s requires capabiliti es for mov e me nt of the specimen in orthogonal direc ti ons in its ow n plan e as well as in a direction perpe ndic ular to th e s pecim e n plane, and for an optical mi croscope to vi e w the area of interes t, (2) To elimin a te the di stortion effec ts of geo metric proj ec tion on the flat film, carry out orientation s tudies, and for almost alJl a ttice spacin g s tudies, th e capability of or ie ntin g th e specim e n by mean s of a mlcrogoniometer controlled from outside th e vac uum system is necessary, (3) The pattern cen ter position must be found for almost all lattice spacing studies and as an origin for orientation studies. Therefore, one must be able to mark the position of the pattern center precisely, …”

“…interce pted by a Rat photographic film , comc sectIOns corresp ondin g to each monoc hromatic component (s uch as Kal, Ka2, and Kf3) of th e primary be am will be r ecorded s uperimposed upon a general background blacke nin g. These co ni c sections have been refe rred to as Kossel lines in honor of tha t pioneer of the divergent beam x-ray tec hniqu e [1]. 1 The entire photograph is ofte n called a Kossel pattern or, if the x-ray source happe ns to be external to th~ diffract in g c rystal , the photograph may be called a pseudo-Kossel pattern [2].…”