Micropyretic synthesis of NiAl containing Ti and B

The effect of alloying additions of Ti and B on the process of micropyretic synthesis on NiAl and on the microstructure of the synthesized alloy was e xamined. It was observed that the combustibility of the quaternary alloy is good despite the presence of the alloying elements because of an additiona l combustion reaction between Ti and B. The microstructure of the quaternar y alloy was found to consist primarily of the NiAl and Ti boride phases. Th e effect of preheating of the specimen prior to synthesis on the process of synthesis was also examined. It was observed that preheating not only can change the morphology of the phases but also influence the nature of the ph ases present in the alloy. The mechanism of the formation of the two phase microstructure during the synthesis from the elemental powders was establis hed by stopping the combustion front and by carrying out a detailed microst ructural characterization of regions around the stopped combustion front.