Improving in plasticity of orthorhombic Ti2AlNb-based alloys sheet by high density electropulsing
(1. School of Astronautics, Harbin Institute of Technology, Harbin 150001, China;
2. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
2. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: In order to optimize the ductility of orthorhombic Ti2AlNb-based alloys sheet, Ti-22Al-27Nb sheet was treated by high density electropulsing (Jmax=6.80-7.09 kA/mm2, tp=110 μs) under ambient condition. Microstructures were observed by SEM, and the tensile properties were also studied using uniaxial tension tests. The experimental results show that electropulsing can refine the microstructures of Ti-22Al-27Nb sheets. The specimen with the fine and homogeneous microstructures has good plasticity, and its elongation reaches 19.4%. The mechanism about the effect of electropulsing treatment on the microstructure of Ti-22Al-27Nb sheets was discussed. It was thought that the increase in nucleation rate during phase transformation and a very short treating time were regarded as the main reasons of producing smaller grains and increase in the plasticity by electropulsing.
Key words: Ti2AlNb-based alloys; electropulsing treatment; plasticity; grain refinement; microstructure; nucleation rate; phase transformation