Synthetic processes of uniform nickel aluminides by reactive infiltration and post hot-pressing of infiltrated precursors

Abstract

Abstract The suitable condition for processing of uniform nickel aluminides by squeeze casting of aluminum melt into porous nickel preforms was investigated. The reactivity among nickel preforms and aluminum melt depended largely on the initial particle size of nickel. Uniform aluminides could be fabricated by in situ reaction at relatively low-temperatures when fine nickel particles are used. Large defects, which had an eutectic structure, were sometimes observed. These defects were formed by the subsequent infiltration into voids caused by rapid shrinkage due to self-propagating reaction. Dense and uniform aluminides could also be obtained by post hot-pressing of the synthesized aluminides at 1473 K. A large amount of fine Al 2 O 3 particles, which were formed by reaction with impurity oxygen, precipitated during the post hot-pressing.