Iron base are the most commonly used material in powder metal parts. Iron parts with heat treatment the hardness can reach HRC 30-58. Stainless steel only 410 and 416 can do heat treatment.
Iron, alloyed steel, stainless steel (only 416), bronze, copper, can easily process secondary machining: sizing, grinding, machining, hole drilling...etc.
Soft magnetic materials are easy to magnetize and demagnetize. Most of magnetic materials of industrial interests are ferromagnetic materials.