Orientation-dependent microstructure development during high-rate shear deformation of copper

ABSTRACT

The microstructure transformations in copper subjected to high-rate deformation via dynamic channel angular pressing (DCAP) have been examined after one and four DCAP passes using electron backscattering diffraction. The focus was on the interrelation between microstructure and texture evolution and on the role of deformation twinning in these processes. During the first pass, a mesoscopic banding is shown to be the main mechanism of grain fragmentation, while the texture is qualitatively similar to that of face-centered cubic metals subjected to equal channel angular pressing, including the presence of characteristic texture components C, A₁ and A₂. A correspondence between structural elements and texture components occurs. Specifically, the mesobands have orientations near either an A₁ or A₂ ideal orientation, whereas the matrix has an orientation near C. Inside the A₁-bands, microtwins with orientations near A₂ are observed. Detailed analysis of the A₂-bands suggests that they may be of twinning origin. Similar orientation dependence of microstructure, though on a much finer scale, is observed after four DCAP passes. Based on the microstructure examination, it was suggested that mesoscopic banding together with deformation twinning continue to be principal mechanisms of grain refinement until the fourth pass, resulting in the formation of ultrafine-grained structure.

KEYWORDS:

• High-rate plastic deformation
• copper
• microstructure
• deformation twinning
• texture
• electron backscattering diffraction

Disclosure statement

No potential conflict of interest was reported by the author(s).

ORCID

N. Yu. Zolotorevsky http://orcid.org/0000-0002-0185-5452

Notes

1 The value obtained is smaller than the grain/subgrain size of 200–300 nm determined earlier by TEM for the copper subjected to four ECAP passes [28]. This seems to be the natural consequence of the high-rate deformation used in the case of DCAP [9].

Additional information

Funding

This work was supported by the Ministry of Science and Higher Education of the Russian Federation under State Assignment on the theme ‘Structure’, reg. № АААА-А18–118020190116–6.