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Recent studies have highlighted the beneficial role of rhenium in enhancing the properties of superalloys. Even a slight alloying addition of rhenium can lead to a significant improvement in mechanical properties, particularly at elevated temperatures. This finding is particularly intriguing in the context of powder-based additive manufacturing techniques, which enable the utilization of powder mixtures to create metal matrix composites (MMCs) or facilitate in situ alloying. The primary objective of the current research was to examine the impact of rhenium on the powder bed fusion-laser beam (PBF-LB) process of IN 625, a specific alloy. Despite its limited solubility in the as-built state, the addition of rhenium was found to have a notable influence on increasing the ultimate tensile strength (UTS). This effect became even more pronounced after heat treatment (solution treatment), which induced a higher dispersion of rhenium and other precipitates within the material. The experimental results demonstrated that the specimen with the addition of rhenium exhibited a remarkable UTS of 900 MPa, in contrast to the 700 MPa exhibited by the wrought material. This research clearly showcases that, despite its poor dispersion characteristics, the incorporation of rhenium can lead to a substantial increase in the strength of the material. [ABSTRACT FROM AUTHOR]

The development of powder metallurgy methods in recent years has caused traditional casting methods to be replaced in many industrial applications. Using such methods, it is possible to obtain parts having the required geometry after a process that saves both manufacturing costs and time. However, there are many material issues that decrease the functionality of these methods, including mechanical properties anisotropy and greater susceptibility to cracking due to chemical segregation. The main aim of the current article is to analyze these issues in depth for two powder metallurgy manufacturing processes: laser powder bed fusion (LPBF) and hot-pressing (HP) methods—selected for the experiment because they are in widespread use. Microstructure and mechanical tests were performed in the main manufacturing directions, X and Z. The results show that in both powder metallurgy methods, anisotropy was an issue, although it seems that the problem was more significant for the samples produced via LPBF SLM technique, which displayed only half the elongation in the building direction (18%) compared with the perpendicular direction (almost 38%). However, it should be noted that the fracture toughness of LPBF shows high values in the main directions, higher even than those of the HP and wrought samples. Additionally, the highest level of homogeneity even in comparison with wrought sample, was observed for the HP sintered samples with equiaxed grains with visible twin boundaries. The tensile properties, mainly strength and elongation, were the highest for HP material. Overall, from a practical standpoint, the results showed that HP sintering is the best method in terms of homogeneity based on microstructural and mechanical properties. [ABSTRACT FROM AUTHOR]