Mechanism for self-formation of Al matrix composites using nitridation-induced manufacturing processes

In our previous work, we introduced a simple process of manufacturing Al matrix composites (AMCs) without vacuum or external pressure, which employs an exothermic reaction accompanying the nitridation of Al, called nitridation-induced self-forming Al composites (NISFAC). This paper investigates the self-sintering mechanism of AMCs in this NISFAC to understand why self-sintering only occurs in nitrogen (no other gas atmospheres) and surface modification of Al and SiC particles occurs during heating only in this atmosphere. The surfaces of the Al powder change from an oxide film to an Al(O)N film, an Al droplet containing Al(O)N, Al–O, and then come into contact with the liquid Al, thereby improving wettability between the liquid Al and SiC particles. By employing combined examination of microscopic and thermal analysis, we found that the interface structures of the prepared AMCs are advantageous in very close contact.