Recent Advances on Mechanical Properties of Metallic Materials under Extreme Conditions
The response of metallic materials to extreme conditions is a major concern for engineering applications. For example, the experimentally detectable defects (such as voids, precipitates, dislocation loops and stacking fault tetrahedrons, etc.) are formed in metallic materials through the bombardment of high energy particles, and these irradiation-induced defects can dramatically affect the macroscopic mechanical behaviors of metallic materials. Temperature is another important factor influencing the deformation of metallic materials, especially for high temperature applications. Recently we proposed a multi-scale model to predict the mechanical properties of metallic polycrystals under extreme conditions, ranging from micro-scale (dislocation level) to meso-scale (grain level) to macro-scale (polycrystalline level). At the dislocation level, the evolution law of microstructures (e.g. defects, interfaces and forest dislocations) affected by temperature is characterized through the dislocation-microstructure interaction. At the grain level, the temperature dependent hardening behavior is evaluated by considering their influences on the critical shear resistance to dislocation movement. At the polycrystalline level, the elastic-visco-plastic self-consistent method is applied for the scale transition from individual grains to the macroscopic polycrystal, taking into account not only the crystal orientation distribution but also the interaction between adjacent grains. The proposed model can predict the effects of microstructure and temperature on the mechanical properties of metals, including dislocation hardening, interface hardening and softening under high temperature.