Irene Beyerlein1,Shuozhi Xu1,Justin Cheng2,Nathan Mara2
University of California, Santa Barbara1,University of Minnesota2
Irene Beyerlein1,Shuozhi Xu1,Justin Cheng2,Nathan Mara2
University of California, Santa Barbara1,University of Minnesota2
Even after their introduction some decades ago, metallic nanostructured, multi-phase composites have continued to draw world-wide interest due to their exceptionally high strength and hardness and outstanding tolerance to extreme conditions, such as elevated temperatures, irradiation, and high-rate impact. The combination makes them an exciting class of materials for meeting the demands of future applications, such as nuclear power reactors, propulsion systems, and microelectromechanical devices. At present, however, they are not suitable for long-time service due to insufficient toughness and a greater tendency to develop shear localizations than their more coarsely structured counterparts. A unique and important feature of these materials is the physical dominance of biphase interfaces, the atomically thick boundary between the dissimilar phases in the composite. The deformation response of the biphase interface and interactions with moving dislocations can have a profound effect on overall material behavior, suggesting the appealing potential to control its localization tendencies via design of the interface itself. In this talk, we will focus on the behavior of nanolayered nanocomposites made with extraordinarily “thick” interfaces under mechanical deformation. We will discuss efforts to characterize and design the morphology, size, and chemistry of the interface, especially in its third dimension (normal to the interface plane). Results from a model developed to simulate the dynamic interactions of individual dislocations and these 3D interfaces under applied stress will be presented. The talk will share our findings to date, which indicate that both the macroscopic and microscopic responses are sensitive to interface thickness and through-thickness chemical gradients. We will conclude with a discussion on the intriguing possibility to design 3D thick interfaces to attenuate shear concentrations and postpone instabilities without sacrificing strength.