An extrusion apparatus and process are disclosed that produce high-performance extrusion structures. The extrusion apparatus includes a shear tool that applies a rotational shear force and an axial extrusion force to the face of a billet material that plasticizes the billet material. Plasticized material is extruded through an extrusion die along the length of the inner bore of the shear tool which yields hollow and solid extrusion structures. The process refines the microstructures of the extrusion structures and extrusion materials.
STATEMENT REGARDING RIGHTS TO INVENTION MADE UNDER FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
 This invention was made with Government support under Contract DE-AC05-76RLO-1830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.