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Yang Z.-Q.,Henan University of Science and Technology | Liu Y.,Henan University of Science and Technology | Liu Y.,Henan Collaborative Innovation Center for Non Ferrous Materials General Technology | Tian B.-H.,Henan University of Science and Technology | And 3 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013

The true stress-true strain curves of 20 vol% TiC particle reinforced dispersion-strengthened copper matrix composite were investigated by compression tests at 450-850°C with the strain rate of 0.001-1 s-1 using the Gleeble-1500D simulator. The dynamic recrystallization critical conditions were established according to the work hardening rate approach. The results show that the softening mechanism of the dynamic recrystallization is a feature of flow stress-strain curves of the composites, and the peak stress increases with the decreasing deformation temperature or the increasing strain rate. The inflection point in the lnθ-ε curve appears and minimum value of -∂(lnθ)/∂ε-ε curve is presented when the critical state is attained for this composite. The critical strain and peak critical decrease with the decreasing strain rate and the increasing deformation temperature. There is linear relationship between critical strain and peak strain, i. e. εc/εp=0.5276. Source


Yang Z.,Henan University of Science and Technology | Liu Y.,Henan University of Science and Technology | Liu Y.,Henan Collaborative Innovation Center for Non Ferrous Materials General Technology | Tian B.,Henan University of Science and Technology | And 3 more authors.
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2014

In order to determine the dynamic recrystallization behavior of TiC/Cu-Al2O3 composites and provide theoretical reference for the development of hot working process parameters. Using the Gleeble-1500D simulator, the hot simulation compression tests of TiC/Cu-Al2O3 composites were conducted at deformation temperature of 450-850℃, the strain rate of 0.001-1 s-1 and total strain of 0.7.The true stress-strain curves of TiC/Cu-Al2O3 composites were fitted and analyzed. The work hardening rate of TiC/Cu-Al2O3 composites was obtained. The critical conditions of dynamic recrystallization were studied by the inflection point criterion of work hardening rate-strain curves and the minimum value criterion of corresponding partial derivative curves. The results indicate that the softening mechanism of the dynamic recrystallization is a feature of true stress-strain curves of the composites, and the peak stress increases with the decrease of deformation temperature or the increase of strain rate. The inflection point in the work hanrdening rate-strain curve appears and the minimum value of the corresponding partial derivative curve is presented when the critical state is attained for this composite. The critical strain decreases with the increasing deformation temperature and the decreasing strain rate. There is linear relationship between critical strain, peak strain and Zener-Hollomon parameter. Source


Yang Z.-Q.,Henan University of Science and Technology | Liu Y.,Henan University of Science and Technology | Liu Y.,Henan Collaborative Innovation Center for Non Ferrous Materials General Technology | Tian B.-H.,Henan University of Science and Technology | And 3 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2014

The true stress-true strain curves of 20 vol% TiC-dispersion-strengthened copper composite were investigated by compression tests at 450-850°C with strain rate of 0.001-1 s-1 using the Gleeble-1500D simulator. The nonlinear equation of stress-true strain was obtained with nonlinear fitting method. Work hardening rate was obtained. The dynamic recrystallization critical conditions were established. Furthermore, the predicting model of critical strain was determined by the Zener-Hollom on parameter approach. The results show that the true stress-true strain curves can be accurately characterized by nonlinear equation, the softening mechanism of the dynamic recrystallization is a feature of flow stress-strain curves of the composites. The inflection point in the lnθ-ε curve appears and minimum value of -∂(lnθ)/∂ε-ε curve is presented when the critical state is attained for this composite. The critical strain increases with the increasing strain rate and the decreasing deformation temperature. There is linear relationship between critical strain and peak strain, i. e. εc=0.5276εp. The predicting model of critical strain is described by the function of εc=7.91×10-3Z0.0736. Source


Yang Z.-Q.,Henan University of Science and Technology | Liu Y.,Henan University of Science and Technology | Liu Y.,Henan Collaborative Innovation Center for Non Ferrous Materials General Technology | Tian B.-H.,Henan University of Science and Technology | And 3 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013

Using Gleeble-1500D simulator, the high-temperature plastic deformation behavior and dynamic recrystallization behavior of 10 vol%TiC/Cu-Al2O3 composite were investigated at 450-850°C with strain rate of 0.001-1 s-1 and total strain of 0.7. The results show that the softening mechanism of the dynamic recrystallization is a feature of high-temperature flow stress-strain curves of the composite, and the peak stress increases with the decreasing of deformation temperature or the increasing of strain rate, and the composite belongs to temperature and strain rate sensitive material. Based on the true stress-strain curves, the activation energy of the composites is 170.737 kJ/mol. Meanwhile, the inflection point in the θ-σ curve appears and has a minimum value in the -dθ/dσ-σ curve when the critical state is attained for this composite. The critical strain increases with the increasing strain rate and the decreasing deformation temperature. There is linear relationship between critical strain and peak strain, i. e., εc/εp=0.704. The predicting model of critical strain is described by the equation: εc=1.48×10-2Z0.0765. Source

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