Coating Metal Powders with Different Metals Under Ultra-low Oxygen Atmosphere for Tuning Material Functions

Metal powders usually have oxide films on their surfaces. When used in powder metallurgy, these surfaces form oxygen-rich grain boundaries, which could harm the material's performance. We developed a technique to coat metal powders with different metals directly on their oxide-free surfaces under ultra-low oxygen atmosphere. This enables us to form a thin and uniform covering layer on each particle. Even when the content of the coating material is of the order of single wt%, it can greatly improve the material performance through a direct metal-metal interface without oxides in between. By sintering the coated powder, the grain boundary properties, which affect various material properties, can be controlled by this technique. We will show some examples of how this technique can tune the material function.