Cross-Contaminations in Powder Bed Fusion: Influence of Copper Alloy Particles in Nickel-Base Alloy Feedstock on Part Quality

Abstract

When two or more different metal powders are processed on a single additive manufacturing (AM) machine, cross-contaminations can occur. This is particularly relevant to the consecutive processing of different materials on a powder bed fusion (PBF) machine through material changes as well as simultaneous processing of different materials via multi-material PBF. However, uncertainty about tolerable foreign particle percentages in metal powder feedstock limits the applicability of material changes and multi-material PBF. Two alloys which are of particular relevance to the aerospace industry are nickel-base alloy 2.4668 and copper alloy CW106C. In multi-material applications, 2.4668 mainly serves as a structural, load-bearing material. Therefore, this study investigates the influence of defined quantities of copper alloy particles in nickel-base alloy feedstock on metallurgical structure and static tensile strength. Foreign particle inclusions were dissolved in the matrix material and formed a solid solution. No material deteriorations were observed for contamination levels up to 20 particle percent (part.%). Etching revealed a nonhomogeneous solid solution with Cu-rich areas. Contamination levels up to two particle part.% CW106C in 2.4668 showed no influence on ultimate tensile strength and a limited influence on fracture elongation. At five part.% contamination, both properties deteriorated and inferior material qualities were observed. Fractography showed a similar fracture behavior for all of the contamination levels examined. Implications for the aerospace industry by the material combination examined are made on the basis of the results presented.