  The influence of Zr additions (in the form of ZrH2 particles) on the
microstructure and mechanical properties of IN718 Ni-based superalloy
manufactured by selective laser melting was explored. Fully dense alloys could
be obtained by careful selection of the processing parameters. The addition of
ZrH2 did not modify the microstructure of the alloy but introduced a dispersion
of Zr-rich globular particles of approximately 50 nm in diameter which
increased the strength of the as-printed material at ambient (23C) and high
temperature (550C). Heat treatments of solubilisation followed by aging led to
a fine dispersion of gamma" precipitates that controlled the strength of the
alloy, which was independent of the addition of Zr. Moreover, dynamic strain
ageing was found in the heat treated materials when deformed at 550C. Finally,
the strength of the IN718 deformed perpendicular to the building direction was
higher than that along the building direction, regardless of the heat treatment
and temperature. Computational homogenization simulations showed that the
anisotropy was associated with the strong texture.
