The mechanical properties of crystalline materials can be efficiently optimized using a hierarchical twinned structure.Conventional deformation mechanisms for coherentΣ3 boundaries generally involve three basic model...The mechanical properties of crystalline materials can be efficiently optimized using a hierarchical twinned structure.Conventional deformation mechanisms for coherentΣ3 boundaries generally involve three basic models:cross-slip,partial dislocation step,and full dislocation step.In this study,we report a novel deformation mechanism that allows the co-existence of twin-separation,phase transformations,grain rotation,and cracking,around a triple junction of twin boundaries in a hierarchical twinned highentropy alloy.The deformation mechanisms in the reference high-entropy alloy(Fe-30 Mn-10 Co-10 Cr at.%)were investigated using LAADF-STEM.The triple junction of the hierarchical twinned structure gradually deformed during in-situ strain and showed mechanisms significantly different from that observed in the purely twinned structures.These new mechanisms are referred to as“novel synergetic deformation mechanisms of hierarchical twin boundaries”.Understanding the fundamental mechanisms of the hierarchical twin boundaries under deformation could assist the design of strong and ductile bulk materials with hierarchical twinned structure.展开更多
基金financially supported by the European Research Council under the EU’s 7th Framework Programme(FP7/20072013)/ERC Grant agreement 290998National Natural Science Foundation of China(NSFC)(Grant No.11872380)the Natural Science Foundation of Hunan Province(Grant Nos.2019JJ50750,2020JJ3043)。
文摘The mechanical properties of crystalline materials can be efficiently optimized using a hierarchical twinned structure.Conventional deformation mechanisms for coherentΣ3 boundaries generally involve three basic models:cross-slip,partial dislocation step,and full dislocation step.In this study,we report a novel deformation mechanism that allows the co-existence of twin-separation,phase transformations,grain rotation,and cracking,around a triple junction of twin boundaries in a hierarchical twinned highentropy alloy.The deformation mechanisms in the reference high-entropy alloy(Fe-30 Mn-10 Co-10 Cr at.%)were investigated using LAADF-STEM.The triple junction of the hierarchical twinned structure gradually deformed during in-situ strain and showed mechanisms significantly different from that observed in the purely twinned structures.These new mechanisms are referred to as“novel synergetic deformation mechanisms of hierarchical twin boundaries”.Understanding the fundamental mechanisms of the hierarchical twin boundaries under deformation could assist the design of strong and ductile bulk materials with hierarchical twinned structure.
