Grain refinement kinetics and strengthening mechanisms in Cu–0.3Cr–0.5Zr alloy subjected to intense plastic deformation

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 654; pp. 131 - 142
• Main Authors: Zhilyaev, A.P., Shakhova, I., Morozova, A., Belyakov, A., Kaibyshev, R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 27.01.2016
• Subjects: Aging; COPPER ALLOYS (40 TO 99.3 CU); Copper base alloys; CuCrZr alloy; DEFORMATION; Equal channel angular pressing; Grain refinement; Intense plastic deformation; KINETICS; MATHEMATICAL ANALYSIS; Mathematical models; MECHANICAL PROPERTIES; Microstructure; MICROSTRUCTURES; PLASTIC STRAIN; Solid solution; Solution strengthening; STRAIN; Strengthening; Aging; Intense plastic deformation; Solid solution; CuCrZr alloy; Grain refinement
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2015.12.038

The ultrafine-grained microstructures, mechanical properties and electrical conductivity of a Cu–0.3%Cr–0.5%Zr alloy subjected to equal channel angular pressing (ECAP) at a temperature of 400°C to a total strain of 1, 2, and 4 were investigated. The ultrafine-grained microstructure resulting from progressive increase in the misorientations of strain-induced low-angle boundaries during the multiple ECAP process is considered as a type of continuous dynamic recrystallization. The multiple ECAP process resulted in substantial strengthening of the alloy. The yield stress of CuCrZr alloy in the initial solution treated condition (ST) increased from 65MPa to 476MPa after four ECAP passes at 400°C. For the aged condition (AT), the yield stress increased from 170MPa to 511MPa after four passes. The strengthening was attributed to the grain refinement and high dislocation densities evolved via large strain deformation. Bacon–Kocks–Scattergood modification of the Orowan model is sufficient for acceptable description of the precipitation hardening of AT specimens during ECAP processing; this finding is in excellent agreement with the experimental data. The discrepancy between the experiment and model for ST specimens disappears after taking into consideration additional precipitating of the supersaturated solid solution during preheating and ECAP processing. Total strengthening and experimental YS of CuCrZr alloy in solution treated (left) and aged (right) conditions as a function of accumulated strain or number of ECAP passes evaluated TEM and EBSD. [Display omitted]