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Interfaces in heterostructures of crystalline materials could strongly affect the slip of dislocations. Such interfaces have become one of the most popular methods to tailor material strength and ductility. This review focuses on the interaction of dislocations and interfaces in heterostructures, in which at least one component is metallic, as investigated by molecular dynamics, in order to systematically summarize our understanding about how dislocations interact with the interfaces. All the possible heterostructures of metallic materials are covered, such as twin boundaries, grain boundaries, bi-metal interfaces and metal/non-metal interfaces. Dislocations may either penetrate the interfaces by inducing steps into the interfaces or dissociate within the interfaces, depending on the type and orientation of the interface as well as the applied strain. Related dislocation interactions at the interface are also presented. In addition, we also discuss the effect of dislocation types, of applied strain and of the deformation method on the interaction of dislocations and interfaces.

The exploitation and application of recycled concrete are more and more extensive in latest years. But the research on the mechanics characteristic of recycle concrete under cyclic loading is very little. Six types of recycled concrete specimens were made in laboratory. After they were cured for a certain age, we have made a series of cycling loading tests on them. In the tests the maximum and minimal stress ratio, the loading frequency and loading waveform were all considered. The mechanics characteristic of recycled concrete under static loading and cyclic dynamic loading were contrasted. After analyzing the test results, we could get that the maximum stress and minimal stress ratio, the loading frequency and loading waveform influenced the unloading and loading modulus of recycled concrete directly in the tests, and the fatigue life of recycled concrete changed with the loading method.