Metal hybrids processed by high-pressure torsion: synthesis, microstructure, mechanical properties and developing trends

Abstract

The tradeoff between strength and ductility has long been identified as the 'Achilles' heel' of the mechanical properties in engineering applications. Metal hybrids processed by severe plastic deformation (SPD) have gained significant attention in recent years, as they have shown potential for enhancing strength and ductility simultaneously through different heterostructured designs. Among SPD processes, high-pressure torsion (HPT) is considered the most effective in grain refinement and offers excellent versatility for synthesising new materials with a wide variety of experimental setups and processing parameters. This review article describes the current state-of-the-art of metal hybrids processed by HPT, characterised by heterogeneous microstructures (i.e. nanoscale and/or microscale), through a comprehensive study of their synthesis-microstructure-property relationships. The potential of HPT-processed hybrids is highlighted and discussed along with their limitations. Suggestions are provided with the aim to advance current research trends towards future application in high-impact technologies, including the biomedical and microelectronic industries.

Turbulent shear flow of solids

“…The principal SPD technique used to that end was high-pressure torsion (HPT) [10]. The process involves shear flows of two or more metals giving rise to vortices at their interfaces, which lead to random oscillations of the flow velocity and vigorous mixing of the metals, cf., e.g., [11][12][13]. The flow pattern and the shape of inclusions of the harder of the constituent metals within the relatively soft matrix resemble the picture observed in free shear flows of fluids.…”

“…Investigations of SST as a stochastic nonlinear phenomenon is of great scientific significance, as it has certain universality and can occur at different length scales: from laboratory experiments to processes in the Earth's lithosphere [20]. The phenomenon is also of practical importance, as SST opens an avenue for solid-state mixing and physicochemical reactions under high pressure, whose potentialities in materials engineering can hardly be overestimated [13,21]. Indeed, SST offers an ecologically advantageous alternative to conventional metallurgical processing.…”

An Overview on the Effect of Severe Plastic Deformation on the Performance of Magnesium for Biomedical Applications

“…The performance of magnesium implants can be improved by the incorporation of other materials into composites [ 110 ]. High-pressure torsion provides the opportunity to consolidate different metallic materials, including magnesium, into a bulk sample in which the structure is significantly refined [ 111 , 112 ]. Thus, recent papers have exploited this procedure, and different composites and hybrids have been produced using HPT.…”

Primary recrystallization of a magnesium hybrid material fabricated by high-pressure torsion

“…During the last decade, the use of the high-pressure torsion (HPT) technique became not only well established for achieving significant grain refinement but also became a powerful methods for synthesizing new hybrid metals [5,6]. Moreover, HPT processing has the ability to change the deformation behaviour and the dynamic recrystallization kinetics of Mg-based alloys by comparison with conventional thermomechanical processing [7,8].…”