Progress of porous Al-containing intermetallics fabricated by combustion synthesis reactions: a review

Recently, research on the preparation of porous Al-containing intermetallic compounds using combustion synthesis (CS) reaction in combination with a space holder process has been gradually increased, in order to improve the porosity and obtain the pore structures with controllable pore morphology and pore size. The reaction mechanism for the M–Al (M = Ti, Ni, Fe, Nb, and Cu) system is closely related to the state of aluminum (e.g., solid or liquid phase) and is greatly affected by processing parameters such as particle size, Al content, heating rate, compacting pressure, sintering temperature, content, and the type of pore-forming agents. Once the sintering temperature causes the appearance of one liquid phase in the reaction system, the remaining solid reactant quickly dissolves into the molten one to improve the surface contact and then generate considerable heat to complete the combustion reaction. Interestingly, the actual temperature change of the sample during the sintering process is accurately detected, and the transparent observation of the reaction state is also realized, which provides a new vision for further exploration of the reaction mechanism of other compounds.