Many properties of materials are incompatible with each other or even completely exclusive. Here, we proposed a new concept in view of the trade-off paradox of material properties, which is to macrodirectionally design the microstructure of materials according to their specific service requirements to accurately use the properties of materials to the extreme. By using this concept, we successfully solved the paradox of high strength and high conductivity of copper contact wire in a high-speed train. Our concept can be used to solve the other property paradoxes of functional and structural materials.
Keywords: electrical conductivity; macrodirectional design of microstructure; material property paradox; strength; thermal stability; ultrafine grained copper.