Theory of designing the gradient microstructured metals for overcoming strength-ductility trade-off

Gradient microstructure design has been found to be an effective approach to significantly produce the utmost advanced structural metallic materials, which have a signature in mechanical characteristic of strength-ductility-hardenability combination. In this work, a physical theory and mechanism-based numerical model are developed for sophisticatedly designing the gradient microstructured metals. It considers the gradient distribution of grain size, twin, martensite and austenite in a metallic alloy. The numerical results are validated through experiments. The mechanical performance of high strength, large ductility and considerable hardenability is achieved and their trade-off is successfully overcome.