| Abstract: | Superplasticity of the TiNp/2014AI composite prepared by powder metallurgy method was investigated by tensile tests conducted at different temperatures (773, 798, 818 and 838 K) with different strain rates range from 1·7×10° to 1·7×10?3s?1. Results show that a maximum elongation of 351% is achieved at 818 K and 3·3·10?1s?1. At different deformation temperatures, the curves of m value can be divided into two stages with the variation of strain rate and the critical strain rate is 10?1 s?1. Superplastic deformation activation energy in the TiNp/2014AI composite is 417 kJ mol?1, which is related to liquid phase formation at triple points of grain boundaries and interfaces between the matrix and the reinforcement. Superplastic deformation mechanism of the TiNp/2014AI composite is grain boundary sliding accommodate mechanism when the strain rate is lower than 10?1 s?1, and transfers to grain boundary sliding accommodation mechanism plus liquid phase helper accommodation mechanism when the strain rate is higher than 10?1 s?1 |
