Microstructure characterization of high‐purity aluminum processed by dynamic severe plastic deformation

Abstract

Fine‐grained aluminum (700–1000 nm) was processed by dynamic severe plastic deformation of coarse‐grained (3 mm) pure aluminum (99.999 wt.%). The resulting microstructure was characterized by transmission electron microscopy (TEM) and X‐ray profile analyses. It is observed that the grain size determined by TEM departs from measurements made by X‐ray profile analysis. In the latter case, the average crystallite size determined over the global crystallographic or on the deformation‐induced texture components, namely {123} 〈 751 〉, {100} 〈 011〉, and {223} 〈 154 〉, yields similar values (∼225 nm). By contrast, the dislocation density determined on these texture components is about two times higher than the one measured on the global texture. The difference might be related to the specificities of the induced crystallographic texture.

High Purity Ultrafine‐Grained Nickel Processed by Dynamic Plastic Deformation: Microstructure and Mechanical Properties

“…[25,26] It is observed here that the initial grain boundary structure, even though distorted, is still visible on the periphery of the sample (Figure 2c). The discrepancies between TEM and XRD measurement have been reported [25,38] in the case of metallic materials deformed by SPD routes. In general, a L. Farbaniec et al/High Purity Ultrafine-Grained Nickel non-uniform grain-refinement occurs due to DPD as suggested by EBSD analysis (Figure 2c and d).…”

“…However, TEM investigations revealed that the difference in the grain sizes and grain-size distributions along the diameter of the impacted disk is small. [25] This can be attributed to a more planar dislocation slip mechanism due to the lower SFE energy for Ni (%130 mJ Á m À2 [36] ) compared to pure Al (166 mJ Á m À2 [37] ) and also to the higher melting point of the former material. Moreover, the actual step size (0.1 mm) used for EBSD analysis also does not take into account the very small grains detected by TEM.…”

“…[3][4][5] The increase in strength and hardness in metals can be achieved by grain subdivision during plastic deformation. [24][25][26] These studies revealed that strain rate, deformation temperature and stacking fault energy (SFE) play a significant role in dislocation patterning which subsequently results in the formation of new grain boundaries during further straining. [6,7] Among them, high pressure torsion (HPT) and equal channel angular pressing (ECAP) are the most frequently used SPD techniques.…”

Effect of Cross Section Reduction on the Mechanical Properties of Aluminium Tubes Drawn With Variable Wall Thickness

“…That led to the anisotropy of microstructure and mechanical properties in the AA6063 drawn tubes. The anisotropy of microstructure and mechanical properties was also observed in the materials processed by the accumulative roll bonding process [16,17], cold rolling [18], hot rolling [19], severe plastic deformation [20], and dynamic severe plastic deformation [21,22]. Figure 6(b) shows the aspect ratios of the grain size observed in the TD-RD and DD-RD samples as function of the CSR.…”

Ultrafine-Grained Aluminum Processed by a Combination of Hot Isostatic Pressing and Dynamic Plastic Deformation: Microstructure and Mechanical Properties

“…From the HIP-processed specimens, samples 12 mm in diameter and 21 mm in height were cut and submitted to DPD using a drop mass bench as described in previous studies. [20,21] After impact, the sample was deformed into a disk shape 22.5 mm in diameter and 6 mm in height (Figure 2), corresponding to an axial strain of approximately 1.25. During DPD, the impact velocity decreases gradually with increasing strain down to a zero value.…”