Change in Microstructure and Texture during Annealing of Pure Copper Heavily Deformed by Accumulative Roll Bonding

Abstract

Pure copper sheets were heavily deformed up to equivalent strain of 4.8 by the accumulative roll-bonding (ARB) processed and then annealed. The ARB processed copper showed the ultra-fine grained microstructure which consisted of relatively equiaxed grains having grain thickness of about 0.2 mm. The DSC measurement of the ARB processed specimens revealed that the recrystallization temperature significantly decreased with increasing the number of the ARB cycles. The stored energy did not increase so much at later stage of ARB, which corresponded with the change in microstructure. The recystallization behavior of the ARB processed copper was governed by discontinuous recrystallization characterized by nucleation and growth process. Remarkable development of cube texture ({100}h001i) was found in the specimen deformed to the equivalent strain of 3.2 or larger and then annealed. The concentration of the cube recrystallization texture depended on the number of ARB cycles.

Temperature and Strain Rate Dependence of Flow Stress in Severely Deformed Copper by Accumulative Roll Bonding

“…6 consists of a mixture of relatively equiaxed and slightly elongated grains. 12,13) At N ¼ 8, the spacing of high-angle lamellar boundaries of elongated grains was about 370 nm in the present study.…”

“…The microstructure of copper at N ¼ 4 possesses the so-called lamellar boundary structure. 12,13) However, the microstructure for N ! 6 consists of a mixture of relatively equiaxed and slightly elongated grains.…”

Grain Boundary Structure of Ultrafine Grained Pure Copper Fabricated by Accumulative Roll Bonding

“…Furthermore, in order to compare the grain boundaries in the ARB-Cu with equilibrium grain boundaries, the grain boundary energy and structure of h110i STGBs in pure Cu were computed by molecular dynamics (MD) simulation. The electron back-scattering diffraction (EBSD) measurement in the previous study 14) has found that the ARB-Cu had a texture composed of h110i == TD (the transverse direction of the sheet), so that the present observation of the grain boundary structure by HRTEM was carried out along TD. The grain boundary energy and structure simulation was also done for h110i STGBs.…”

Thermal conductivity in yttria dispersed copper

“…Hence, limiting the thermal expansion of copper is highly desirable as a first step to increase its applicability for thermal management applications. There are number of studies discussing the thermal stability of the microstructure of fine, deformed and severe plastically deformed copper [9][10][11][12][13][14]. However, there are very few reports concerning the thermal expansion of copper.…”