showed that the high values of tand and ε0
r and
also high frequencies and large values of the dielectric properties
could produce surface heating. On the other hand, low frequencies
and small values of dielectric properties led to more volumetric
heating [18e20].
SPS introduces many advantages such as joule heating, high-
heating rates, applying pressure during sintering process and
cleaning surface of powders [21,22]. There is doubt about formation
of plasma in spark plasma sintering process among researchers but
this does not detract from its functionality [23,24]. In the case of
aluminum and its composites, conductivity of aluminum is the
effective key in the sintering process. With a conductive sample
material, best results can be achieved by highest possible current
density inside the specimens and cleaning the surface of powders
from oxide layer [25]. Application of pressure during sintering