A method of manufacturing a rotor includes: (a) providing a core shaft; (b) cold spraying alloy powder particles onto the core shaft; (c) controlling the cold spraying to form sections at least of different shape along the core shaft to thereby form a near-net shape rotor; and (d) heat treating the near-net shape rotor to relieve stresses and to form diffusion bonding across interfaces between individual powder particles and the core shaft, and finish-shaping said near-net shape rotor.