Melting of Ni3Al-based intermetallic alloys was successfully accomplis
hed by the Exo-Melt(TM) process by modifying the furnace-loading seque
nce to initiate the highly exothermic NiAl reaction to form superheate
d NiAl liquid initially. Recorded images of the melting process showed
the occurrence of exothermic diffusional reactions between liquid alu
minum and solid nickel melt stock. Combustion synthesis of NiAl and Ni
3Al is also described and compared with the Exo-Melt(TM) process. In c
ontrast to the Exo-Melt(TM) process, the conventional melting practice
of adding aluminum to molten nickel increased the temperature of the
bath from 1600 to 2300 degrees C, and a vapor cloud formed due to the
oxidation of alloying elements. The Exo-Melt(TM) process results in po
wer savings of 47% over conventional melting practices, and the proces
s has been used to melt and cast a total of 8000 kg of Ni3Al-based all
oy. Reaction mechanisms involved in the Exo-Melt(TM) process and conve
ntional melting processes are described and compared with the reaction
mechanisms operating in combustion synthesis.