Processing and Microstructural Characterization of Metallic Powders Produced from Chips of AA2024 Alloy
Accumulated metal waste during machining of aluminum alloys is considered for further recycling to promote environmentally sustainable production. This study aims to characterize the ball-milling process of AA2024 aluminum chips as an alternative to the remelting procedure. The proposed processing modes provide a powder particle size distribution with a d50 of 100–325 μm after 100 min milling. Stearic acid, as a process control agent (PCA), slows down powder refinement if introduced at the early stages of milling. The powder tends to form a flake-shaped morphology owing to the impact of plastic deformation altered by the PCA. Microhardness variation is linked to the joint effect of voids, strengthening phases, mechanically affected zones, and grain structure. Further, the paper reports the crystallite sizes ranging from 25 nm to 45 nm and the lattice strain < 1%. Finally, an outlook on hot-powder compaction and the associated properties of the material are presented.
Dr. Oleg V. Rofman gratefully acknowledges the financial support of the Ministry of Education and Science of the Russian Federation for conducting powder milling and hot compacting experiments in the framework of Increase Competitiveness Program of NUST (MISiS) [No. К4-2017-058], implemented by a governmental decree dated 16th of March 2013, N 211. The microstructural and XRD studies in this work were supported by the RSF [Grant # 17-79-20426]. The authors thank Dr. E. I. Patsera for his assistance with the particle size measurements by static light scattering technique.
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