Published online by Cambridge University Press: 26 February 2011
In order to overcome the brittleness of Nb-Si intermetallic compounds, a novel microstructure control through a eutectic solidification and a eutectoid decomposition reactions has been proposed for obtaining Nb matrix alloys with Nb-silicide dispersion by the present authors. As the additions of Zr and Mg accelerate the eutectoid decomposition rate and spheroidization of Nb-silicide during heat treatment, the effects of these additives on the eutectic microstructure are investigated. The effect of the growth rate during the uni-directional solidification on the microstructure of a selected alloy was examined and it was found that the following eutectoid reaction rate is strongly affected by the growth rate.