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Quasi-Stationary Strength of ECAP-Processed Cu-Zr at 0.5 Tm
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Strain Rate Contribution due to Dynamic Recovery of Ultrafine-Grained Cu–Zr as Evidenced by Load Reductions during Quasi-Stationary Deformation at 0.5 Tm

1
Department of Materials Science, Institute I, University of Erlangen-Nuremberg, Martensstr. 5, D-91058 Erlangen, Germany
2
Institute of Physics of Materials, Czech Academy of Sciences, Žižkova 22, CZ-616 62 Brno, Czech Republic
3
Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA
*
Author to whom correspondence should be addressed.
Metals 2019, 9(11), 1150; https://doi.org/10.3390/met9111150
Received: 24 September 2019 / Revised: 18 October 2019 / Accepted: 21 October 2019 / Published: 26 October 2019
(This article belongs to the Special Issue Dislocation Mechanics of Metal Plasticity and Fracturing)
During quasi-stationary tensile deformation of ultrafine-grained Cu-0.2 mass%Zr at 673 K and a deformation rate of about 10−4 s−1 load changes were performed. Reductions of relative load by more than about 25% initiate anelastic back flow. Subsequently, the creep rate turns positive again and goes through a relative maximum. This is interpreted by a strain rate component ϵ ˙ associated with dynamic recovery of dislocations. Back extrapolation indicates that ϵ ˙ contributes the same fraction of ( 20 ± 10 ) % to the quasi-stationary strain rate that has been reported for coarse-grained materials with high fraction of low-angle boundaries; this suggests that dynamic recovery of dislocations is generally mediated by boundaries. The influence of anelastic back flow on ϵ ˙ is discussed. Comparison of ϵ ˙ to the quasi-stationary rate points to enhancement of dynamic recovery by internal stresses. Subtraction of ϵ ˙ from the total rate yields the rate component ϵ ˙ + related with generation and storage of dislocations; its activation volume is in the order expected from the classical theory of thermal glide. View Full-Text
Keywords: Cu–Zr; ECAP; ultrafine-grained material; deformation; dynamic recovery; transient; load change tests Cu–Zr; ECAP; ultrafine-grained material; deformation; dynamic recovery; transient; load change tests
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MDPI and ACS Style

Blum, W.; Dvořák, J.; Král, P.; Eisenlohr, P.; Sklenička, V. Strain Rate Contribution due to Dynamic Recovery of Ultrafine-Grained Cu–Zr as Evidenced by Load Reductions during Quasi-Stationary Deformation at 0.5 Tm. Metals 2019, 9, 1150.

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