Some variations provide a process for additive manufacturing of a nanofunctionalized
metal alloy, comprising: providing a nanofunctionalized
metal precursor containing metals and grain-refining nanoparticles; exposing a first amount of the nanofunctionalized
metal precursor to an
energy source for melting the precursor, thereby generating a first melt layer; solidifying the first melt layer, thereby generating a first
solid layer; and repeating many times to generate a plurality of
solid layers in an additive-manufacturing build direction. The additively manufactured, nanofunctionalized
metal alloy has a
microstructure with equiaxed grains. Other variations provide an additively manufactured, nanofunctionalized
metal alloy comprising metals selected from aluminum, iron,
nickel,
copper,
titanium,
magnesium,
zinc,
silicon,
lithium, silver,
chromium,
manganese,
vanadium,
bismuth,
gallium, or lead; and grain-refining nanoparticles selected from
zirconium,
tantalum,
niobium,
titanium, or oxides, nitrides, hydrides, carbides, or borides thereof, wherein the additively manufactured, nanofunctionalized
metal alloy has a
microstructure with equiaxed grains.