Properties and Nanostructures of Materials Processed by SPD Techniques

Abstract

Metallic materials usually exhibit higher strength but lower ductility after being plastically deformed by conventional techniques such as rolling, drawing and extrusion. In contrast, nanostructured metals and alloys processed by severe plastic deformation (SPD) have demonstrated both high strength and high ductility. This extraordinary mechanical behavior is attributed to the unique nanostructures generated by SPD processing. It demonstrates the possibility of tailoring the microstructures of metals and alloys by SPD to obtain superior mechanical properties. The SPD-generated nanostructures have many features related to deformation, including high dislocation densities, and high-and low-angle grain boundaries in equilibrium or non-equilibrium states. This paper reviews the mechanical properties and the defect structures of SPD-processed nanostructured materials.

The New SPD Processing Trends to Fabricate Bulk Nanostructured Materials

“…Recent years have seen growing interest in developing SPD processes to fabricate bulk nanostructured metals and alloys with unique properties [1][2][3][4]. This approach, as an alternative to nanopowder compacting, is based on microstructure refinement in bulk billets using severe plastic deformation (SPD): that is, heavy straining under high imposed pressure [1].…”

A Computational Investigation into the Effect of Equal Channel Angular Processing on the Mechanical Properties of Severely Deformed ZK 60 Alloy Validated by Experiments

“…It is worth to mentioning here that, the major bottlenecks for using Mg as appropriate selection in biomedical applications is the metal's poor corrosion resistance, its underwhelming ductility and its relatively low strength, which have always been an obstacle to the community in the development of Mg technology (Hu et al, 2017). The poor ductility of Mg is resultant from its hexagonal closed packed crystal structure, which lacks sufficient independent slip systems to accommodate the global strain (Zhu and Huang, 2001).…”

“…Moreover, Zn is soluble in Mg in quantities up to 6.2 wt.% (Song et al, 2019;Li et al, 2011). Zn improves the mechanical properties of Mg, its corrosion behavior and its ductility (Zhu and Huang, 2001;Tong et al, 2010). In addition, (Ding et al, 2010) found that the addition of zirconium reduces the corrosion rate and improves the strength of magnesium.…”

“…SPD is a metal forming process where a very high strain is forced on a bulk solid without changing the overall dimensions of the solid which leads to an exceptional grain refinement (Valiev and Langdon, 2006). SPD techniques are some of the most successful techniques in refining existing materials into nanostructured materials (Zhu and Huang, 2001). It is worth mentioning here that the utilization of SPD techniques leads to grain refinement and to the break-up of second-phase particles which improves corrosion resistance (Qiang et al, 2014).…”

“…One of the modern SPD techniques that reduce the grain size to sub-microcrystalline scale (0.1-0.2 m) is Equal Channel Angular Pressing (ECAP) process (Zhu and Huang, 2001;El Garaihy, 2020). In recent years, the results of the ECAP on Mg alloys have been investigated.…”