Mechanical alloying, microstructure and properties of Nb-16Si alloy

Nb-16at.% Si bulk alloys were prepared by uniaxial hot pressing from mechanically alloyed powder mixtures. It is shown that the addition of appropriate absolute ethyl alcohol significantly restrained the agglomeration of particles and accelerated the milling process. Moreover, besides the solid solution of Si into Nb lattice, significant iron contamination dissolved into Nb to develop another Nb solid solution after a long milling time. Sintering results indicate that, with sintering temperature increasing from 1200 to 1500 degrees C, densities and mechanical properties of sintered alloys increased and the morphology of constituent phases (niobium solid solution, Nb5Si3 and Nb3Si in micron dimension) changed from irregular shape to nearly equiaxed one. However, as for the material hot pressed at 1600 degrees C, the microstructure became coarser and the properties were not improved because of the weakening of fine-grain contribution. (C) 2009 Elsevier B.V. All rights reserved.