Effect of the environment on the morphology of Ni powder during high-energy ball milling

Abstract

In high energy ball milling process, the milling environment plays an important role on tailoring the microstructure and properties of metal powder. The refining behavior regarding ball milling of Ni powder in different atmospheres (air and argon gas) is investigated in this study. We find that the Ni powder is coarsened (from 28.4 ± 0.5 μm to 38.5 ± 13.9 μm) after milling in argon gas for 16 h. By contrast, its grain size and particle size are smaller than 20 nm and 2 μm respectively after milling in air. By analyzing the morphology and the chemical composition of the milled powders, the effect of different environments, including ambient air, dry air, and ambient air with ethanol, on ball milling process was investigated. The adsorption of oxygen is believed to play a key role in the refinement of Ni powder. The results provide a new insight into the environmental effect during ball milling, and lead to a new way for refining grain size and particle size of FCC metal powders in high energy ball milling.