For the same sample type, the hardness after solution
and aged treatments was higher than the as-forged as a result of
solution strengthening and age hardening, respectively. Comparing the Al–Cu alloy with the corresponding h-BN/Al–Cu composite
under the T6 treatment, the hardness of the composite was increased by 17%, 12.6% and 14.3% with d50¼35, 12 and 2 μm Al
powder, respectively, due to the addition of the h-BN powder
particles. It was indicated that despite the significantly low content (3 wt%) of the h-BN powder particles in the composite, its
influence on the macroscopic mechanical properties of the material was prominent. Also, it was reflected that the densification
degree of the h-BN reinforced Al matrix composite by the semisolid powder forging was very high, since lower density (higher
porosity) must cause lower material hardness.