For the reaction medium consisting of aluminum particles clad by nickel, experimental results on heat transport mechanisms as well as microstructural transformations that occur in the combustion front, are presented. It is shown that by changing the density of the reaction mixture. the primary mechanism of heat transfer in the reaction front can be varied: radiation for low, gas heat conduction for intermediate and heat conduction through condensed skeleton for high sample densities. Also it appears that reaction triggers at the melting point of aluminum and refractory shell (Ni) prevents the reaction medium from rapid agglomeration. Finally, by experiments conducted under low gravity, it is confirmed that combustion of clouds of such complex particles can be achieved in inert atmosphere.