Targeted microstructural authoring through additive manufacturing of metals

Abstract Metal three-dimensional printing—also known as additive manufacturing (AM)—provides a unique opportunity for materials engineers to locally tailor the microstructure of engineering alloys over a range of length scales. Although multiple metal AM processes exist, the market is dominated by laser powder bed fusion (L-PBF) systems. Properly applied, L-PBF has the potential to allow localized “authoring” of the metallurgical architecture in a number of ways, including the careful manipulation of key processing parameters or using advanced beam shaping technologies to locally control cooling rate through important phase-transformation temperatures. These strategies are, in effect, locally changing the thermal history of the material being fabricated. From a metallurgical perspective, these strategies fall within the well-established processing–structure–properties paradigm, despite their reliance on modern, highly specialized equipment. In this article, we examine how some of these emerging strategies are being used to locally tailor the microstructure in AM alloys and reflect on how this presents opportunities to “dial-in” site-specific mechanical properties in high-performance engineering parts. Graphical abstract