Behavior of Nb and Cu–Nb Composites under Severe Plastic Deformation and Annealing

Abstract

Nowadays potentialities of obtaining bulk nanostructured materials with unique properties by various techniques of severe plastic deformation (SPD) are comprehensively studied, and niobium, being a refractory, but plastic enough metal, is an ideal object for such studies. Besides, niobium is a metal of special interest as an advanced functional material, being one of the main constituents of such important electrotechnical materials as high-strength CuNb composites and multifilamentary Nb 3 Sn-based and NbTi superconductors. The present paper is an overview on evolution of Nb microstructure under SPD via different routes and under large plastic deformation by cold drawing of composite wires (in a Cu matrix). The main attention in this paper is paid to the original studies of the authors (with their coauthors), but the available publications on the topics considered are involved and reviewed as well.

High‐pressure torsion of SiO2 quartz sand: Phase transformation, optical properties, and significance in geology

“…However, the grain size is drastically reduced after HPT processing and the number of diffracted points in the SAED analysis are increased to form a ring pattern in Figure 4D (this pattern was taken from the d area in Figure 4B). Grain refinement by HPT processing is a result of plastic strain effect, which was reported in various metallic 53–55 and nonmetallic 56–58 materials. On the contrary, in Figure 4E, the diffraction points in SAED disappear and a hollow pattern corresponding to amorphous SiO 2 appears (this pattern was taken from the e area of Figure 4B).…”

Improved Photocatalytic Hydrogen Evolution on Tantalate Perovskites CsTaO3 and LiTaO3 by Strain-Induced Vacancies

“…Fifth, the average grain size for both materials after HPT processing is ∼40 nm (excluding the amorphous regions). The occurrence of grain refinement by HPT processing is a natural consequence of plastic strain effect, which was reported in various metallic − and nonmetallic − materials. Moreover, HPT-induced partial amorphization is not a rare phenomenon, as it was reported in several materials, especially intermetallics and multicomponent alloys, although HPT-induced partial crystallization was also reported in some amorphous alloys .…”

“…It is found that straining by HPT is quite effective to reduce the bandgap and improve the photocatalytic activity of both CsTaO 3 and LiTaO 3 . It should be noted that the HPT method is mainly used as a severe plastic deformation (SPD) method for producing nanograined phases in metallic − and nonmetallic − materials. However, a few studies showed the potential of the method for producing high-pressure or highly strained phases with large oxygen or nitrogen vacancy concentration and enhanced photocatalytic activity such as columbite–TiO 2 , rocksalt–ZnO, columbite–TiO 2 /rocksalt–ZnO composite, defected α-Al 2 O 3 , and GaN–ZnO oxynitride …”

Analysis of processing variables in Equiangular Channel Press deformations

“…The ECAP technique aims to introduce a severe plastic deformation to a material without changing the cross-section of the sample, in this way it is possible to refine the material by the number of passes through the matrix, increasing the level of deformation (Popov et al, 2019;Segal et al, 1997;Xu et al, 2005).…”