• The fourth family includes all nanomaterials formed by nanometer sized grains
(layers, rods or equiaxed crystallites) dispersed in a matrix of different
chemical composition. Precipitation hardened alloys typically belong to this
family. Eg. Nanometer sized Ni3Al precipitates dispersed in a nickel matrix-
generated by annealing a supersaturated Ni-Al solid solution- are an example
of such alloys. Most high-temperature materials used in modern jet engines
are based on precipitation-hardened Ni3Al/Ni alloys.
A large part of this definition has been described in an article by Gleiter.iv,v