Quantitative Characterization of Microstructure of Pure Copper Processed by Ecap

Abstract

Orientation imaging microscopy (OIM) allows to measure crystallic orientations at the surface of a material. Digitalized data representing the orientations are processed to recognize the grain structure and they are visualized in crystal orientation maps. Analysis of the data firstly consists in recognition of grain boundaries followed by identification of grains themselves. Knowing the grain morphology, it is possible to characterize the grain size homogeneity and estimate structural parameters related to the physical properties of the material. The paper describes methods of imaging and quantitative characterization of the grain boundary structure in metals based on data from electron backscatter diffraction (EBSD). These methods are applied to samples of copper processed by equal-channel angular pressing (ECAP).

Hardness and Microstructure Homogeneity of Pure Copper and Iron-Chromium Alloy Processed by Severe Plastic Deformation

“…The result concluded that the grain refinement and shear strain rapidly promoted the UFG structure and homogeneous hardness due to high equivalent strain at the ECAP process. The HAGB fraction of pure copper was smaller than that of the iron-chromium ally due to the recovery and recrystallization process during the ECAP process [30][31][32][33][34]. The microstructure showed the larger lamellar structure and coarser grain in the first-pass compared to the fourth pass of ECAP.…”

“…The EBSD analysis revealed the recrystallized grain by showing the LAGB on the micrograph, promoting the UFG structure. The accumulated energy strain and partial recrystallization affected HAGB formation in the first pass of ECAP on both materials [30,35]. The structure in the sub-surface was more equiaxed grain than in the middle of the billet since the plastic deformation imposed in the sub-surface was more prominent than before.…”

“…The microstructure of the ECAP process was uniform after several ECAP processes. The shear strain distribution along the transverse plane during the ECAP process was associated with microstructure evolution due to dislocation annihilation, recovery, and recrystallization [30][31][32][33][34]. The inhomogeneity factor was calculated by considering the standard deviation and average of the value including boundary spacing, aspect ratio, and hardness on the grain size and normal and rolling directions.…”