Friction stir processing can also be used to improve the microstructural properties of powder metal objects. In particular, when dealing with aluminium powder metal alloys, the aluminium oxide film on the surface of each granule is detrimental to the ductility, fatigue properties and fracture toughness of the workpiece. While conventional techniques for removing this film include forging and extrusion, friction stir processing is suited for situations where localized treatment is desired.