High strength and good electrical conductivity in Cu–Cr alloys processed by severe plastic deformation

• Published in: Materials letters Vol. 153; pp. 5 - 9
• Main Authors: Dobatkin, S.V., Gubicza, J., Shangina, D.V., Bochvar, N.R., Tabachkova, N.Y.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.08.2015
• Subjects: Cu–Cr alloys; Electrical properties; Hardness; High pressure torsion; Ultrafine-grained structure; X-ray techniques; Cu–Cr alloys; High pressure torsion; Electrical properties; Hardness; X-ray techniques; Ultrafine-grained structure
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2015.03.144

Ultrafine-grained (UFG) microstructures in Cu–Cr alloys were processed by high pressure torsion (HPT). The improved hardness was accompanied by a reduced electrical conductivity due to the large amount of grain boundaries. The effect of heat-treatment after HPT-processing on the hardness and the electrical conductivity was studied for different chromium contents (0.75, 9.85 and 27wt%). For low Cr concentration (0.75%) the electrical conductivity increased considerably above 250°C, however the hardness decreased concomitantly. At the same time, for high Cr content (9.85% and 27%) the hardness was only slightly reduced even at 500°C, while the electrical conductivity increased to a similar level as before HPT due to grain boundary relaxation and decomposition of Cu–Cr solid solution. Our study demonstrates the capability of SPD-processing and subsequent heat-treatment to achieve a combination of high strength and good electrical conductivity. •Bronzes containing 0.75%, 9.85% and 27% Cr were subjected to high pressure torsion.•With increasing Cr content the hardness rises due to grain size reduction to 40nm.•Heat-treatment after HPT increases electrical conductivity of the alloys.•With increasing Cr content the stability of UFG microstrcucture was improved.•Heat-treatment after HPT yields both high hardness and good conductivity.