In-situ alloying in powder bed fusion: The role of powder morphology

Abstract

Abstract In-situ alloying has been proven as a cost-effective, flexible and advantageous method for laser powder bed fusion (LPBF). Novel alloy development and exploration of, for example high entropy alloys in additive manufacturing, can benefit from this, due to the large number of potential elemental combinations and graduations that can be alloyed in-situ at relatively low cost. However, studies to date have not reported the role of powder characteristics in mixed feedstocks, which may in turn have significant impacts on the process and resultant bulk material properties. This has not been explored with in-situ alloying in literature thus far. In the present work, 4 different powder blends were prepared, processed with LBPF and characterized to reveal the relationships between the particle size distribution (PSD), the powder morphology and their effect on the rheology, powder bed density, bulk density, microstructure and chemical homogeneity. For this purpose, various commercial and elemental powders with different morphology and PSD were used for powder blending. It is shown that a highly homogenous alloy can be created using spherical, bi-modally distributed powder containing between 21 and 30 vol%