Some New Trends in SPD Processing for Fabrication of Bulk Nanostructured Materials

Abstract

During the last decade severe plastic deformation (SPD) has become a well established method of materials processing used for fabrication of ultrafine-grained materials with attractive properties. Nowadays SPD processing is rapidly developing and is on the verge of a transition from lab-scale research to commercial production. This paper focuses on several new trends in the development of SPD techniques for effective grain refinement. The paper also presents new SPD processing routes to produce bulk nanocrystalline materials.

Producing bulk ultrafine-grained materials by severe plastic deformation

“…54,[59][60][61][62] This evolution is revealed in several ways. First, both pure metals and commercial alloys are currently under extensive research and the latter have a great potential for special applications.…”

“…Second, growing attention is being directed within the SPD community to the development of economically feasible continuous production methods for the processing of UFG metals and alloys. [61][62][63] As an example, two different processing routes, including ECAP, were used recently for the systematic fabrication of long rods from nanostructured titanium materials for medical applications. 61 Specifi cally, using a combination of ECAP and thermomechanical treatments with a commercial-purity titanium, it was possible to achieve a yield stress of 1,100 MPa and ultimate tensile strength of 1,230 MPa together with a reasonable elongation to failure of ~14%.…”

“…[61][62][63] As an example, two different processing routes, including ECAP, were used recently for the systematic fabrication of long rods from nanostructured titanium materials for medical applications. 61 Specifi cally, using a combination of ECAP and thermomechanical treatments with a commercial-purity titanium, it was possible to achieve a yield stress of 1,100 MPa and ultimate tensile strength of 1,230 MPa together with a reasonable elongation to failure of ~14%. 64 Using this procedure, titanium rods were fabricated with diameters of 6.5 mm and lengths of more than 800 mm and with variations in the mechanical properties along their lengths of not more than ±5%.…”

Bulk nanostructured titanium fabricated by hydrostatic extrusion

“…After demonstrating the feasibility of fabrication of nanometals, now the challenge is to produce bigger elements [9][10][11][12][13]. The aim of this study was to optimize the fabrication of nano-Ti rods with diameters suitable for industrial applications.…”

Development of a high-strength high-conductivity Cu−Ni−P alloy. Part II: Processing by severe deformation

“…Based on severe deformations, recently, several novel processing methods, including mechanical milling, torsion under high pressure, equal channel angular extrusion, and accumulative roll-bonding, were developed to fabricate various structural and functional alloys with superior properties. [1][2][3][4][5][6] A beneficial combination of mechanical and functional properties could be associated with a promising structural state that had a grain size of tens to hundreds nanometers. [7][8][9][10][11][12] The structural mechanism responsible for evolution of the submicrocrystalline state during large-strain processing was generally discussed as a kind of continuous dynamic recrystallization, that was the formation of geometrically necessary sub-boundaries, like dense dislocation walls, and a gradual rise in subboundary misorientations up to values typical of conventional high-angle grain boundaries.…”