A method of forming a bearing cage is generally disclosed herein. The method includes (i) forming a bearing cage from either titanium or a titanium alloy; and (ii) applying a plasma-nitriding treatment to at least one surface of the bearing cage to form a compound layer of titanium nitride including TiN and Ti2N on an outer region of the at least one surface. Step (ii) further forms a diffusion zone adjacent to the outer region, in one aspect. A surface hardness of the bearing cage that is treated by the plasma-nitriding step is at least 1000 HV. The bearing cage is configured to be used in a turbofan, turboprop, or turboshaft engine or in a helicopter gearbox, in one aspect.