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Surface finishing is challenging in the context of additively manufactured components with complex geometries. Magnetic abrasive finishing (MAF) is a promising surface finishing technology that can refine the surface quality of components with complex shapes produced by additive manufacturing. However, there is insufficient study regarding the impact of MAF on microstructure–property relationships for additively manufactured builds, which is critical for evaluating mechanical performance. In this work, we studied the effects of different combinations of MAF and heat treatment steps on the microstructure–property relationships of Inconel 718 superalloys made by laser powder bed fusion (LPBF). The application of MAF was found to significantly reduce the surface roughness and refine the grain size of aged alloys. Moreover, MAF was able to increase the alloy elongation, which could be further influenced by the sequence of MAF and different heat treatment steps. The highest elongation could be achieved when MAF was performed between homogenization and aging processes. This work indicates that an effective combination of surface finishing and heat treatment is critical for the improvement of alloy performance. Furthermore, it demonstrates a promising solution for improving the performance of LPBF Inconel 718 by integrating MAF and heat treatment, which provides new perspectives on the post-processing optimization of additively manufactured alloys. [ABSTRACT FROM AUTHOR]

Phase stability of AlxCo0.2Cr0.2Ni0.2Ti0.4 − x (x = 0.1, 0.2 or 0.3, in mole fraction) high entropy alloys (HEAs) in both as-cast and as-annealed states is studied through thermodynamic calculations and experimental characterization. Both disordered bcc_A2 and ordered bcc_B2 phases are observed in the as-cast alloys and exhibit rather high stability with slow diffusion kinetics during post-annealing. Influences of Al/Ti content ratio on lattice constant, phase stability and hardness are discussed through comparison between computation and experiments. It is found that higher Al/Ti ratio stabilizes phases dramatically for both bcc_A2 and bcc_B2 phases, which are observed in all three as-cast AlxCo0.2Cr0.2Ni0.2Ti0.4 − x HEAs. The comparison between calculation of phase diagrams (CALPHAD) model prediction and experimental results indicates a promising approach to design HEAs by applying the CALPHAD database. Moreover, the current CALPHAD database still needs to be further improved for a reliable parametric design of alloy composition and post-heat treatment. [ABSTRACT FROM AUTHOR]

Due to the temperature gradients generated from the complex heating and cooling cycles during Laser Powder Bed Fusion, strong columnar texture is often observed in the as-built Inconel 718 alloys together with notable residual stress, which leads to anisotropic properties of manufactured alloy components. We found that, in contrast to the typical homogenization performed at 1065°C, a simple higher temperature homogenization step conducted at 1180°C can effectively remove the residual stress and reconstruct the microstructure by introducing recrystallization. More importantly, it can introduce isotropic microstructures and tensile properties, which are critical in engineering applications. Additionally, owing to the elimination of the residual stress, the precipitation of the strengthening phase γ″ becomes more isotropic (i.e., with three variants precipitating) during the subsequent aging process. This work is conducive to developing effective post-heat treatment of additively manufactured alloys for better performance. [Display omitted] [ABSTRACT FROM AUTHOR]