Thermo-mechanical behavior and constitutive modeling of in situ TiB₂/7050 Al metal matrix composites over wide temperature and strain rate ranges

The thermo-mechanical behavior of in situ TiB₂/7050 Al metal matrix composites is investigated by quasi-static and Split Hopkinson Pressure Bar compression tests over a wide range of temperature (20~30 °C) and strain rate (0.001~5000 s^-1). Johnson-Cook and Khan-Liu constitutive models determined from curve fitting and constrained optimization are used to predict the flow stress during deformation. In addition, another Johnson-Cook model calculated from an orthogonal cutting experiment and finite element simulation is also compared in this study. The prediction capability of these models is compared in terms of correlation coefficient and average absolute error. Due to the assumptions in orthogonal cutting theory, the determined Johnson-Cook model from cutting cannot describe the material deformation behavior accurately. The results also show that the Khan-Liu model has better performance in characterizing the material's thermo-mechanical behavior.