Reactive infiltration processing was investigated in the NiAl system using nickel-powder and nickel-wire preforms. Inhomogeneous microstructures were often obtained with powder preforms which had high surface-to-volume ratio, low permeability and irregular infiltration paths. Homogeneous NiAl could be obtained with nickel-wire preforms which had lower surface-to-volume ratio, higher permeability and regular infiltration paths. NiAl composites reinforced with short molybdenum fibers and long tungsten and sapphire fibers were also fabricated by reactive infiltration.
Christian Leinenbach, Irene Ferretto