In Situ Synchrotron X‐Ray Diffraction during High‐Pressure Torsion Deformation of Ni and NiTi

Abstract

p 3 γ torsion , using the van Mises criterion of plastic flow. If there is some outward flow of material between the two anvils and a corresponding reduction in the value of h, it can be taken into account by adding the true (compressive) strain. The size of

Significance of strain rate in severe plastic deformation on steady-state microstructure and strength

“…Another source of discrepancies between other studies [12][13][14][15][16][17][18][19][20] and ours may be the fact that the ex-situ and in-situ measurements of strength do not combine because of static recrystallization effects that may take place after the ex-situ experiments, i.e. during the unloading event before the ex-situ strength measurements are done [38,39]. Concerning the in-situ experiments such as those reported in [14], the way of torque measurement may be different for different facilities used, i.e.…”

Recent <i>In Situ</i> Experimental and Theoretical Advances in Severe Plastic Deformations, Strain-Induced Phase Transformations, and Microstructure Evolution under High Pressure

“…Still, an important result in Ref. 25) was that during pressure release after SPD of Ni at 8 GPa, the crystallite size was increased by more than a factor of 2, and dislocation density was decreased by about a factor of 3, confirming the importance of in situ studies under pressure. Even the application of hydrostatic pressure can significantly increase the dislocation density and reduce the crystallite size, e.g., by a factor of 2 for Zr.…”

“…78) They were broadly applied for high-pressure studies in DAC in perpendicular geometry of iron 79) (including PTs), ultrafine-grained metals, 80,81) tantalum at megabar pressure, 82) tungsten carbide, 83) and various geological materials. 8491) Perpendicular diffraction geometry is used by the SPD community during HPT 24,25) (which we discussed in Introduction) and for the high-pressure sliding 92) and compression 93) (Fig. 3(b)).…”

“…Several attempts of in situ X-ray diffraction during HPT with metallic anvils use diffraction with the beam orthogonal to the compression direction, 24,25) called perpendicular geometry. However, x-ray patterns in this case are averaged over very heterogeneous fields, including nondeformed material, and just one value is measured for the prescribed load and rotation angle.…”