The Effect of Severe Plastic Deformations on Phase Transitions and Structure of Solids

Abstract

This paper presents data on the study of phase transitions in solids under pressure with shear deformation. Carbon, silicon and zirconium were used as model substances. The studies were carried out by electron microscopy and optical (Raman) spectroscopy. A description of a high pressure diamond anvil shear cell is also provided.

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).…”

The Effect of Shear Deformation on C-N Structure under Pressure up to 80 GPa

“…Before loading the g-C 3 N 4 specimen, it was kept in a vacuum at a temperature of 95 °C for two hours.Three experiments were conducted with different initial pressure loading levels: (a) 20 GPa; (b) 53 GPa; and (c) 70 GPa. On achieving an initial pressure, shear deformation was applied to the sample by means of rotating one of the anvils around the load axis [ 17 ]. At each initial pressure, the anvil was rotated by 20° and returned to its initial position.…”

“…After applying shear deformation, the pressure increased in the sample to 25, 57, and 79 GPa, accordingly. Pressure increase was induced by a jump in the elastic module and volume [ 17 ]. After removing the pressure and extracting the gasket from the diamond cell, the obtained material was examined.…”

“…However, there is a way to overcome the reaction activation barrier by applying shear stress under high pressure [ 16 , 17 ]. In the present study, we investigate the effect of shear stress on the behavior of the C-N phase under high pressure, in the shear DAC (SDAC).…”

<i>In Situ</i> Synchrotron X-ray Analysis: Application of High-Pressure Sliding Process to Ti Allotropic Transformation

“…© 2020 The Japan Institute of Metals and Materials A d v a n c e V i e w in hydrostatic conditions, but for the case of DAC, plastic deformation was intentionally introduced by rotation of one diamond anvil to the other, following the Bridgman's idea, 13) Blank and co-workers are the first to generate shear strain using DAC, 77,78) and extensive studies with straining by DAC were carried out by Levitas and coworkers 79) and most recently by Nomura et al 80) For the case of multi anvil setup, two differential rams were incorporated in the upper and lower guide flames so that generation of plastic strain up to 30% was feasible. 81,82) Plastic strain was also introduced using a rotational Drickamer apparatus for the in situ examination, which were designed to examine creep behavior of geological materials under high pressures and high temperatures, 8387) with a basic principle involved in the Bridgman's idea.…”