TEM, XRD and Raman scattering of germanium processed by severe deformation

A study on the capability of equal channel forward extrusion process

“…This increased lattice micro-strain by adding ECFE pass number may be related to the surplus volume of grain boundaries through the generation and movement of dislocations. It is previously found that this lattice micro-strain is a measure of lattice constants dispensation resulting by the crystal imperfections including lattice dislocation, grain boundary triple junction, contact or sinter stress, stacking fault, twins, coherency stress and related defects [16,30,31]. These findings are in good agreement with the present work where strength and hardness 13 improvement rate are decreased at the higher pass numbers.…”

“…Eq. (1) represents the W-H relationship in which β is the full width at half maximum (FWHM) of the Bragg peak, θ is the analyzed Bragg angle, k is the shape factor (≈ 0.9), λ is the X-ray wavelength, d is the average crystalline size, ԑ is the lattice micro-strain and f(ԑ) is a defined function [16,17]. In addition, to decouple the contribution of instrumental broadening of a diffractometer (β inst ) and specimen-dependent broadening (β obs ) effects on the Bragg peak breadth, Gaussian profile was applied according to Eq.…”

Producing Bulk Ultrafine-Grained Materials by Severe Plastic Deformation: Ten Years Later

“…The application of HPT to Ge and GaAs also produces nanograins (Fig. 9a), [100][101][102] and a similar PL peak is observed owing to the nanograin formation by HPT processing and subsequent annealing (Fig. 9b).…”

Oxidation Resistance of Nanocrystalline Alloys

“…These different atomic arrangements can be attributed to the presence of interfacial region and crystalline region [51]. Similarly, EXFAS investigation of nanocrystalline Fe and Pd indicated a large reduction in the atomic coordination number, supporting the idea of a very disordered structure at the interfaces [52][53][54][55][56]. Positron-lifetime spectroscopy measurements showed a large density of vacancy-like defects in grain boundaries and relatively large free volume at the triple points arising from misorientationinduced atomic instability of these sites [57].…”