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Superplasticity of high strength Al based alloys produced by thermomechanical treatment
The current research aimed to investigate characteristics of superplasticity of two high strength aluminum alloys, the one that contains fine coherent particles of Al3(Zr,Sc) phase and the other that contains both coherent fine Al3Zr and coarse Al3Ni particles. It has been established that the bimodal distribution of Al3Zr and Al3Ni particles significantly improves superplasticity due to active dynamic poligonisation and recrystallisation during superplastic deformation and high temperature stability of grain structure. Superplastic behaviour at tensile tests under constant strain rate and initial strain rate was compared and effective activation energy of superplastic deformation was calculated. It was found that the alloy with bimodal particles distribution exhibited 1100-1200% elongation at strain rates of 1×10-2 s- 1 - 1×10-1 s-1 and 440 oC. Finite element simulation and superplastic forming of model parts "T-tube" type were performed.