High-Pressure Torsion and Severe Plastic Deformation in Metal Processing

High-pressure torsion (HPT) and other severe plastic deformation (SPD) techniques have emerged as transformative methods for tailoring the microstructure and properties of metallic materials. By imposing ultrahigh shear strains under compressive loads, HPT refines grain sizes to the ultrafine and nanometre regimes, introduces high densities of lattice defects and stimulates phase transformations. These structural modifications yield exceptional combinations of strength, ductility and functional performance, from enhanced fatigue resistance in structural alloys to improved hydrogen storage in energy materials. Beyond conventional alloys, SPD has enabled the synthesis of novel composites, metastable solid solutions and heterostructured metals, demonstrating applications in superconductivity, photocatalysis and biomedical implants. The global significance of such advances lies in the ability to process bulk components without melting or alloying additions, offering energy-efficient routes to high-performance materials and opening avenues across sectors from aerospace to sustainable energy technologies.

Research from Nature Portfolio

Recent studies have revealed the complex flow instabilities that govern microstructural mixing during ultrahigh strain shearing. Experiments on multilayered metal systems demonstrate how layer folding, vortex formation and delamination lead to controlled phase redistribution and mechanical mixing at the micrometre scale. Numerical models treating the metal phases as nonlinear viscous fluids reproduce these instabilities, linking metallurgical phenomena to geological folding processes. In parallel, new work on bulk aluminium–magnesium systems has achieved record supersaturation of magnesium in an aluminium matrix by combining diffusion bonding with HPT. This process produces a fully nanocrystalline alloy with homogeneous hardness and unprecedented solute content, illustrating the capacity of torsional deformation to generate metastable alloys inaccessible by conventional casting or powder routes.

High-Pressure Torsion and Severe Plastic Deformation in Metal Processing publication trend

The graph below shows the total number of articles in high-pressure torsion and severe plastic deformation in metal processing across all publications each year (not limited to Nature Index journals).

Technical terms

Severe plastic deformation (SPD): A set of metal-working processes that impose very high strains to refine microstructure without changing overall dimensions.

High-pressure torsion (HPT): An SPD technique in which a disk‐shaped sample is subjected to high compressive pressure and simultaneous rotational shear.

Ultrafine-grained structure: A microstructure in which grain sizes are reduced to typically less than 1 µm, leading to enhanced mechanical strength.

Nanocrystalline alloy: A material consisting of grains smaller than 100 nm, characterised by high defect densities and unique functional properties.

Diffusion bonding: A solid-state joining process where atomic diffusion under pressure creates metallurgical bonds without melting.

Phase transformation: A change in the crystal structure or composition of a material, often induced by strain and defect accumulation.

References

1. From unlikely pairings to functional nanocomposites: FeTi–Cu as a model system. Materials Today Advances (2023).
2. Severe plastic deformation for producing superfunctional ultrafine-grained and heterostructured materials: An interdisciplinary review. Journal of Alloys and Compounds (2024).
3. Nanomaterials by severe plastic deformation: review of historical developments and recent advances. Materials Research Letters (2022).
4. Mixing instabilities during shearing of metals. Nature Communications (2017).
5. Using high-pressure torsion to process an aluminum–magnesium nanocomposite through diffusion bonding. Journal of Materials Research (2015).