After annealing the cryo-rolled sample, each diffraction peak of
the Cu matrix splits into two components. As an example, Fig. 3
shows reflection (220) for the sample annealed for 20 min. For
comparison, the same reflection for the cryo-rolled specimen is
also presented. The splitting of the peaks is probably caused by
the development of an inhomogeneous solute atom distribution
in the Cu matrix during annealing, resulting in a variation of the
lattice parameter of the Cu matrix. Each line profile was evaluated
by fitting it with the sum of two profile components having different
Bragg-angles which correspond to two distinct regions of the
matrix having different average lattice parameters. It should be
noted that most probably the description of the distribution of
the solute concentration by only two distinct solute contents is a
simplification. Nevertheless, this procedure characterizes the
inhomogeneity of the chemical composition of the matrix. The
Ag solute concentrations in the two regions of the matrix have
been determined from the lattice parameters of the two Cu phases
obtained from the sub-profile positions and shown as a function of
annealing time in Fig. 4a. It is noted that the solid curves in Fig. 4
serve only as guide to eyes. The volumes with low and high Ag contents
are referred to as Regions 1 and 2, respectively. The peaks of
Regions 1 and 2 are at higher and lower diffraction angles, respectively.
In Region 2, the solute Ag content increased from 1 at.% to
2.6 ± 0.3 at.% within 5 min annealing and it decreased slightly to
1.9 ± 0.3 at.% with increasing annealing time up to 75 min. For
longer durations of heat-treatment the solute Ag concentration in
Region 2 was not determined due to the low volume fraction of this
region (see below). In Region 1, the solute Ag concentration