Steady non-Newtonian flows in copper and iron aluminide at elevated temperatures

On the basis of dislocation climb and mobility, a steady-state non-Newtonian flow law is derived for two metallic and one intermetallic material, namely electrolytic tough pitch copper, phosphorus alloyed pure copper, and Fe24AlMo iron aluminide. The purpose is to develop a flow law applicable to the finite element simulation for hydrodynamic flow of incompressible metals. The model can accurately represent the experimental flow stress values and the viscosity of the materials. The mathematical form of the model is similar to that of the free-volume approach, which is used for liquids and amorphous metals. The study indicates that in the temperature and strain-rate regimes that are appropriate to the hot-working processes, the Cohen–Grest model, which is essentially related to the total thermal expansion of fluid, can phenomenologically be extended to the crystalline solid-state materials for the depiction of viscosity data.