抄録
Structural materials that are used in environmental and energy applications are expected to have various properties, such as
strength at both room and elevated temperatures, corrosion and wear resistance, and fatigue strength, simultaneously. Additive
manufacturing (AM), an emerging material processing technology, is highly promising for the development of novel materials by
utilizing the unique thermal history that cannot be achieved in conventional manufacturing. In this review, we focus on high entropy
alloys (HEAs), which generally consist of multiple principal elements in (near) equimolar ratios, and their intersection with AM
technologies. The microstructural evolution during electron beam powder bed fusion and its effects on the mechanical and corrosion
properties are summarized based on the results for an equimolar AlCoCrFeNi HEA. It was demonstrated that in addition to nonequilibrium
solidification in a highly confined melt pool, the subsequent solid-state phase transformation and associated solute
partitioning between the constituent phases during the in-process high-temperature exposure play an important role in the significant
improvement of the alloy performance. Consequently, an excellent combination of mechanical properties and corrosion resistance,
which surpasses that obtained in the conventional casting, was achieved. This obtained knowledge indicates the importance of
optimizing not only the solidification behavior but also the entire thermal history (including post-processing), broadening the alloy
design space, and providing opportunities for developing high-performance alloys for harsh environments.
