Superplastic Behavior of a Cu-Cr-Zr Alloy Subjected to ECAP

Abstract:

A Cu-0.87%Cr-0.06%Zr alloy was subjected to equal channel angular pressing (ECAP) at a temperature of 400 °C up to a total strain of ~ 12. This processing produced ultra-fine grained (UFG) structure with an average grain size of 0.6 μm and an average dislocation density of ~4×10¹⁴ m^-2. Tensile tests were carried out in the temperature interval 450 – 650 °C at strain rates ranging from 2.8´10^-4 to 0.55 s^-1. The alloy exhibits superplastic behavior in the temperature interval 550 – 600 °C at strain rate over 5.5´10^-3 s^-1. The highest elongation-to-failure of ~300% was obtained at a temperature of 575 °C and a strain rate of 2.8´10^-3 s^-1 with the corresponding strain rate sensitivity of 0.32. It was shown the superplastic flow at the optimum conditions leads to limited grain growth in the gauge section. The grain size increases from 0.6 μm to 0.87 μm after testing, while dislocation density decreases insignificantly to ~10¹⁴ m^-2.

• Periodical: Materials Science Forum (Volumes 838-839)
• Pages: 404-409
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.838-839.404
• Online since: January 2016
• Authors: R. Mishnev*, Iaroslava Shakhova, Andrey Belyakov, Rustam Kaibyshev
• Keywords: Cu-Cr-Zr Alloy, Equal Channel Angular Pressing, Microstructure, Superplasticity

References

[1] J. Pilling, N. Ridley Superplasticity in crystalline solids., The Institute of Metals, London, (1989).

[2] K. Neishi, Z. Horita, T.G. Langdon, Achieving superplasticity in ultrafine-grained copper: influence of Zn and Zr additions, Mater. Sci. Eng. A 352 (2003) 129-135.

DOI: 10.1016/s0921-5093(02)00868-7

[3] M. Kawasaki, R.B. Figueiredo, C. Xu, T.G. Langdon, Developing superplastic ductilities in ultrafine-grained metals, Metal. Mater. Trans. 38 A (2007) 1891-1898.

DOI: 10.1007/s11661-006-9000-x

[4] K. Neishi, Z. Horita, T.G. Langdon, Achieving superplasticity in a Cu – 40%Zn alloy through severe plastic deformation, Scr. Mater. 45 (2001) 965-970.

DOI: 10.1016/s1359-6462(01)01119-8

[5] R. Kaibyshev, T. Sakai, I. Nikulin, F. Musin and A. Goloborodko, Superplasticity in a 7055 aluminum alloy subjected to intense plastic deformation, Mater. Sci. Tech. 19 (2003) 1491-1497.

DOI: 10.1179/026708303225008167

[6] R.Z. Valiev, D.A. Salimonenko, N.K. Tresnev, P.B. Berbon, T.G. Langdon, Observations of high strain rate superplasticity in commercial aluminum alloys with ultrafine grain sizes, Scr. Mater. 37 (1997) 1945-(1950).

DOI: 10.1016/s1359-6462(97)00387-4

[7] F. Musin, R. Kaibyshev, Y. Motohashi, G. Itoh, High strain rate superplasticity in a commercial Al – Mg – Sc alloy, Scr. Mater. 50 (2004) 511-516.

DOI: 10.1016/j.scriptamat.2003.10.021

[8] M. Mabuchi, K. Ameyama, H. Iwasaki, K. Higashi, Low temperature superplasticity of AZ91 magnesium alloy with non-equilibrium grain boundaries, Acta Mater. 470 (1999) 2047-(2057).

DOI: 10.1016/s1359-6454(99)00094-4

[9] I.S. Batra, G.K. Dey, U.D. Kulkarni, S. Banerjee, Microstructure and properties of a Cu – Cr – Zr alloy, J. Nucl. Mater. 299 (2001) 91-100.

DOI: 10.1016/s0022-3115(01)00691-2

[10] R. Mishnev, I. Shakhova, A. Belyakov, R. Kaibyshev, Deformation microstructures, strengthening mechanisms, and electrical conductivity in a Cu – Cr – Zr alloy, Mater. Sci. Eng. A 629 (2015) 29-40.

DOI: 10.1016/j.msea.2015.01.065

[11] H. Jazaeri, F.J. Humphreys, The transition from discontinuous to continuous recrystallization in some aluminium alloys II – annealing behavior, Acta Mater. 52 (2004) 3251–3262.

DOI: 10.1016/j.actamat.2004.03.031