Tensile behavior of bulk nanocrystalline aluminum synthesized by hot extrusion of ball-milled powders

The deformation behavior of bulk nanocrystalline aluminum down to 48 nm in grain size, produced by hot extrusion of ball-milled powders, has been evaluated by compression and tension tests. Isotropic yield stress increases following the Hall–Petch relationship with decreasing grain size down to 70 nm. However, a positive deviation in the relationship is found for grain sizes below 70 nm, and aluminum with a grain size of 48 nm exhibits a superior yield stress of 500 MPa with ductile failure.