Investigation of the Effects of Processing Parameters on the Morphology, Particle Size and Oxidation Resistance of Recycled Ti-6Al-4V Powders Prepared by Mechanical Milling

Ti-6Al-4V is widely used in both medical and aerospace applications due to its high specific strength as well as excellent corrosion and oxidation resistance. However, because of the high cost of titanium alloys, converting recyclable resources such as waste chips generated in industry into powder form has become crucial. In this context, the mechanical milling method represents an effective, low-cost, and sustainable approach for recycling within closed-loop production systems. In this study, industrial Ti-6Al-4V chips were milled into powder form using methanol as a process control agent (PCA) at concentrations of 0.5, 1, and 2 wt.% and under varying milling durations (30– 360 minutes). The investigation focused on properties such as powder morphology, crystalline structure, oxidation resistance, and apparent density. Milling parameters were set at a 20:1 ball-topowder ratio (BPR) and a rotational speed of 400 rpm. Morphological examinations revealed a transition from flake/fragment-like structures at the beginning to semi-spherical forms, ultimately resulting in spherical powders. For powders milled with 0.5 wt.% PCA, the average particle sizes were observed as D50 ≈ 20 µm, 18.1 µm, and 21.8 µm. The results demonstrated that recycled Ti6Al-4V powders obtained with 2 wt.% PCA during 180–360 minutes of milling exhibited the most suitable properties for use.