In the present study, we fabricated the ultra-fine grained (UFG) Cu-Cr-Zr alloy including fine second phase particles through the accumulative roll bonding (ARB) process and subsequent aging treatment. The nano-sized precipitates dispersing within the UFG matrix significantly enhanced strain hardening, resulting in the simultaneous improvement of uniform elongation and tensile strength.

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The misorientation dependence of discontinuous precipitation (DP) at [001] twist boundaries in Cu-0.75 wt pct Be alloy bicrystals has been systematically investigated in the temperature range 523 to 723 K. A good correlation is found between both the incubation period, , to initiate DP and cell growth rate, v, and the energy of boundaries. The maximum of and the minimum of v occur where the cusps of the boundary energy exist. The formation and growth of DP are easier at higher-energy boundaries. The DP cells at [001] twist boundaries nucleate and grow less than those at [001] symmetric tilt boundaries in the same-alloy bicrystals. A kinetic analysis of DP using the models of Turnbull and Petermann and Hornbogen has yielded grain-boundary diffusion data. Although the activation energy, Q b , of boundary diffusion changes with the models, the values of Q b are smaller than the activation energy for volume diffusion of Be in Cu. The diffusivity in a boundary shows a close correlation with the energy of the boundary. A lower-energy boundary has a lower diffusivity with a larger activation energy and a larger pre-exponential factor.