Constitutive flow behavior and microstructural evolution of 17vol% SiCp/7055Al composite during compression at elevated temperature

摘要

A study is conducted on the flow stress behavior of the spray-deposition processed 17vol% SiCp/7055Al composite through hot compression tests at the temperatures ranging from 250°C to 450°C and the strain rates of 0.001–1s?1, including microstructure evolution. As indicated by the calculation results, the deformation activation energy for the SiCp/7055Al composite is 145.28kJ/mol. All of the obtained flow curves are characterized by dynamic recovery and/or dynamic recrystallization. The hot deformation of the composites in the temperature range of 250–350°C and strain rate region of 1–0.001s?1exhibited the typical characteristics of dynamic recovery. As the deformation temperature increases, the deformation mechanism of the composites shifted to dynamic recrystallization over time. The flow stress showed a decreasing trend with the increase of deformation temperature and the decrease of strain rate, as reflected by a Zener–Hollomon parameter in hyperbolic sine equation. According to the processing map, the optimum hot workability domain is the peak region located around 430–450°C and 0.001–0.03s?1. In addition, the orientation distribution function ODFs were calculated according to the pole figures, which revealed that the textures of the composites are significantly different at the varied hot deformation parameters.