  A large body of literature within the additive manufacturing (AM) community
has focused on successfully creating stable tungsten (W) microstructures due to
significant interest in its application for extreme environments. However,
solidification cracking and additional embrittling features at grain boundaries
have resulted in poorly performing microstructures, stymying the application of
AM as a manufacturing technique for W. Several alloying strategies, such as
ceramic particles and ductile elements, have emerged with the promise to
eliminate solidification cracking while simultaneously enhancing stability
against recrystallization. In this work, we provide new insights regarding the
defects and microstructural features that result from the introduction of ZrC
for grain refinement and NiFe as a ductile reinforcement phase - in addition to
the resulting thermophysical and mechanical properties. ZrC is shown to promote
microstructural stability with increased hardness due to the formation of ZrO2
dispersoids. Conversely, NiFe forms into micron-scale FCC phase regions within
a BCC W matrix, producing enhanced toughness relative to pure AM W. A
combination of these effects is realized in the WNiFe+ZrC system and
demonstrates that complex chemical environments coupled with the tuning of AM
microstructures provides an effective pathway for enabling laser AM W materials
with enhanced stability and performance.
