Many reports already demonstrate the Pb particles exhibit a cube–cube orientation relationship
with surrounding Al matrix ({111}Al//{111}Pb and Al//
Pb) [15–17]. Therefore, we take the Pb particles to be spherical
in form and of mean radius r. When a dislocation penetrates
the particles, they are sheared as shown in Fig. 5. A new surface
is produced during the process of shear, elevating free energy of
the system, as a result, causing strengthening effect [17,18].