Abstract
We studied mechanical alloying (MA) behavior and phase formation during heating of Nb-75mol%Al powder mixture. Average powder size and particle shape changed discontinuously during MA from flake like particle to fme equiaxed particle. MA Powder had changed to granular shape particle having a diameter about 50μm at 270-360ks milling, 20μm at 540-720ks milling, and less than 5μm over 1440ks milling. This phenomenon was due to the phase change from elemental to intermetallic compounds by milling. From the results of DTA and X-ray diffraction, NbAl3 phase formation occurred after Al melting for short time MAed powder up to 360ks. For longer time MAed powder, having fine lamellar structure, NbAl3 phase was formed at 613-623K. Later exothermic reaction became smaller with increasing MA time because of the formation of NbAl3 phase during MA.
