Synthesis of Hybrid Nanocrystalline Alloys by Mechanical Bonding through High‐Pressure Torsion

Abstract

An overview of the mechanical bonding of dissimilar bulk engineering metals through high‐pressure torsion (HPT) processing at room temperature is described in this Review. A recently developed procedure of mechanical bonding involves the application of conventional HPT processing to alternately stacked two or more disks of dissimilar metals. A macroscale microstructural evolution involves the concept of making tribomaterials and, for some dissimilar metal combinations, microscale microstructural changes demonstrate the synthesis of metal matrix nanocomposites (MMNCs) through the nucleation of nanoscale intermetallic compounds within the nanostructured metal matrix. Further straining by HPT during mechanical bonding provides an opportunity to introduce limited amorphous phases and a bulk metastable state. The mechanically bonded nanostructured hybrid alloys exhibit an exceptionally high specific strength and an enhanced plasticity. These experimental findings suggest a potential for using mechanical bonding for simply and expeditiously fabricating a wide range of new alloy systems by HPT processing.

Structure and Mechanical Behavior of Al–Nb Hybrids Obtained by High‐Pressure‐Torsion‐Induced Diffusion Bonding and Subsequent Annealing

“…Severe plastic deformation, the method allowing reaching high strains even in brittle materials without fracture [ 14,15 ] and associated with the maximum permissible concentration of defects, [ 16 ] is also known for its ability to promote the solid state reactions. A particular case of severe deformation, high‐pressure torsion (HPT), has recently been discovered to be an effective way for the synthesis of metal matrix composites that can be performed via solid state welding of powders [ 17–19 ] or a lamellar disc set [ 13,20–23 ] of dissimilar metals. The greatest difference between cases of powder and discs consists in the free surface fraction.…”

Fabrication and characterization of nanostructured immiscible Cu–Ta alloys processed by high-pressure torsion

“…Several processing methods are available for producing nanocrystalline microstructures consisting of solid solutions having different elements. For example, processing through the introduction of severe plastic deformation (SPD) has been used successfully over the last two decades to generate non-equilibrium microstructures in a range of metals and alloys [5][6][7].…”

The Earth's Lithosphere Inspires Materials Design

“…The ability of SPD methods to produce self‐organized structures has been demonstrated in recent publications, [ 22,23,24,27 ] as is illustrated by the images of various systems processed by these techniques in Figure 1II. The striking similarity of the material architectures captured in these images with the metamorphic formations collated in Figure 1I is quite remarkable and evocative.…”