High strain rate superplasticity of ultrafined Ti-10V-2Fe-3Al compact prepared by sintering and isothermal forging

摘要

High strain rate superplasticity was obtained for powder Ti-10V-2Fe-3Al (Ti-1023) alloy prepared by powder sintering and isothermal forging technology. The selected powder was cold isostatic pressed, sintered and isothermal forged to prepare this powder alloy. Tensile testing was conducted at optimum superplastic temperaure of 1023 K with different initial strain rate, and the elongation to failure, the flow stress and the microstructure were analysed. The experiment results exhibited that the microstructure of this powder alloy is extraordinary uniform and fine, resulted in considerable enhancement of optimum initial strain rate increased from 3·3×10−4 s−1 of conventional cast and wrought Ti-1023 alloy to 3·3×10−3 s−1 of this powder alloy. The elongation to failure increased first and then decreased with initial strain rate from 3·3×10−4 to 3·3×10−2 s−1. The strain rate sensitivity m is about 0·46 near initial strain rate of 3·3×10−3 s−1, larger than conventional cast and wrought Ti-1023 alloy. Microstructure observations showed that dynamic recrystallisation and grain growth were present during superplastic deforming.