The present invention relates to a process for hardening an aluminum-based matrix alloy by the dispersion of metallized graphite (MG) with copper and optionally zinc or boron by the agitation in liquid state. By this means, the impregnating of MG particles (reinforcing phase) is increased, facilitating the homogenous distribution in the aluminum-base matrix alloy. The mechanical properties of aluminum or aluminum-based are increased alloys by the process of hardening by dispersion, without affecting the density and electrical conductivity of the alloy.