Influence of HPT Deformation on the Structure and Properties of Amorphous Alloys

Abstract

Recent studies showed that structural changes in amorphous alloys under high pressure torsion (HPT) are determined by their chemical composition and processing regimes. For example, HPT treatment of some amorphous alloys leads to their nanocrystallization; in other alloys, nanocrystallization was not observed, but structural transformations of the amorphous phase were revealed. HPT processing resulted in its modification by introducing interfaces due to the formation of shear bands. In this case, the alloys after HPT processing remained amorphous, but a cluster-type structure was formed. The origin of the observed changes in the structure and properties of amorphous alloys is associated with the chemical separation and evolution of free volume in the amorphous phase due to the formation of a high density of interfaces as a result of HPT processing. Amorphous metal alloys with a nanocluster structure and nanoscale inhomogeneities, representatives of which are nanoglasses, significantly differ in their physical and mechanical properties from conventional amorphous materials. The results presented in this review show that the severe plastic deformation (SPD) processing can be one of the efficient ways for producing a nanocluster structure and improving the properties of amorphous alloys.

High-Pressure Torsion of Non-Equilibrium Hydrogen Storage Materials: A Review

“…Originally, this SPD method was applied to synthesize porosity-free bulk ultrafinegrained materials with submicron crystallite size [20,24,[26][27][28][29], nevertheless, it has recently become a dominant technique to produce low-porosity metallic glass compacts from amorphous ribbon chips [30,31] and reach large plastic strains in bulk metallic glass alloys (BMGs) [32][33][34]. In a novel paper, it was reviewed that HPT can induce significant plasticity in metallic glasses [35], while nanocrystallization of these alloys can also take place [36]. When HPT is applied to immiscible systems for extreme torsion numbers (N = 1500), new metastable phases can form by mixing the elements on the atomic scale [37].…”

Magnetic Materials via High-Pressure Torsion of Powders

“…[3,4] Furthermore, the possibility for phase transformations [5][6][7][8] has been shown as well as the evolution of thermodynamically metastable phases such as supersaturated solid solutions [3,9] or amorphous structures, similar to rapid solidification processes. [10] This variety of HPT-induced microstructural evolutions is accompanied by a noteworthy manufacturing advantage. As initial materials for HPT processing, coarse-grained multi-phase alloys, powder blends of different elements or any other combination of solid starting materials can be used.…”

The Evolutions of Microstructure, Texture and Hardness of A1050 Deformed by HPT at the Transition Area

“…Indeed, a number of experiment characterizations and advanced finite element simulations have already been conducted. Gunderov et al studied the microstructural evolution of HPT-processed amorphous alloys and found that the formation of nanocrystallization depends on the chemical composition of alloys and HPT processing regimes [ 17 ]. Additionally, the influence of defects and dislocations on the electro-resistivity of HPT-deformed nickel have been investigated by Korznikova et al [ 18 ].…”