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In order to obtain the high-temperature flow behavior of Cu-0.5Cr-0.1Zr alloy more accurately, the hot compression test of Cu-0.5Cr-0.1Zr alloy was performed at the strain rates from 0.001 to 1.0 s−1and the deformation temperatures from 600 to 750 °C on a Gleeble-3800 thermo-simulation machine. The results show that the high-temperature flow stress and dynamic recrystallization behavior of Cu-0.5Cr-0.1Zr alloy are affected by strain rate and temperature. The peak stress is obvious under the condition of high temperature and low strain rate, and the flow stress curve shows a clear dynamic recrystallization phenomenon. On the contrary, there is no obvious peak stress at the low temperature and high strain rate, and dynamic softening behavior is mainly based on dynamic recovery. The high-temperature flow stress of Cu-0.5Cr-0.1Zr alloy is expressed as a result of multiple stress actions, such as work hardening, dynamic recovery softening, and dynamic recrystallization softening. The thermal deformation activation energy of this alloy can be calculated as 244.94 kJ/mol. The relationship between the critical stress and the critical strain of dynamic recrystallization and the Zparameter was established through the cubic linear fitting of the work hardening rate curve. Based on the stress–dislocation relation and kinetics of dynamic recrystallization, the constitutive equations before and after critical strain of Cu-0.5Cr-0.1Zr alloy were developed. The predicted stresses of the established DRX constitutive model agree well with the experimental stresses.

ABSTRACTThe influence of Al–Ti–B grain refiners on the microstructures of Zr-containing Al–Zn–Mg–Cu alloy was investigated by optical microscopy and scanning electron microscopy, as well as through tensile and hardness tests. A poisoning effect occurred when the grain refiner was added to the Zr-containing alloy, and the grain size increased significantly. The precipitates in the alloy without the grain refiner were finely distributed, while the phases of the alloy with the Al–Ti–B refiner agglomerated at the grain boundaries, decreasing both the hardness and elongation. The addition of the grain refiner to the alloys markedly increased their hardness and elongation, when coupled with slow cooling, although the peak stress also decreased slightly.

The influence of Al–Ti–B grain refiners on the microstructures of Zr-containing Al–Zn–Mg–Cu alloy was investigated by optical microscopy and scanning electron microscopy, as well as through tensile and hardness tests. A poisoning effect occurred when the grain refiner was added to the Zr-containing alloy, and the grain size increased significantly. The precipitates in the alloy without the grain refiner were finely distributed, while the phases of the alloy with the Al–Ti–B refiner agglomerated at the grain boundaries, decreasing both the hardness and elongation. The addition of the grain refiner to the alloys markedly increased their hardness and elongation, when coupled with slow cooling, although the peak stress also decreased slightly.