Via in situ uniaxial tensile tests in a high-resolution transmission electron microscope,we directly observed a cross-over of plastic deformation mechanisms in a nanocrystalline (nc) Cu thin film containing nano-twin ...Via in situ uniaxial tensile tests in a high-resolution transmission electron microscope,we directly observed a cross-over of plastic deformation mechanisms in a nanocrystalline (nc) Cu thin film containing nano-twin lamellae.For a certain twin lamellae length,the twin lamellae with a larger thickness emit dislocations inclined (Schmidt-factor dislocations,i.e.,S-dislocations) toward the twin boundaries.Upon decreasing the twin lamellae thickness to a critical value,such as approximately 15nm,the plasticity switches toward emission of twinning partial dislocations (T-dislocations) parallel to the twin planes that cause migration of the twin boundaries.The critical twin thickness value also depends on the length of the twin.These results provide direct evidence for thestrengthening and softening mechanisms in nano-twinning structured metals.展开更多
基金Supported by the National Nature Science Foundation of China(10825419,50831001)the National Basic Research Program of China(2009CB623700)。
文摘Via in situ uniaxial tensile tests in a high-resolution transmission electron microscope,we directly observed a cross-over of plastic deformation mechanisms in a nanocrystalline (nc) Cu thin film containing nano-twin lamellae.For a certain twin lamellae length,the twin lamellae with a larger thickness emit dislocations inclined (Schmidt-factor dislocations,i.e.,S-dislocations) toward the twin boundaries.Upon decreasing the twin lamellae thickness to a critical value,such as approximately 15nm,the plasticity switches toward emission of twinning partial dislocations (T-dislocations) parallel to the twin planes that cause migration of the twin boundaries.The critical twin thickness value also depends on the length of the twin.These results provide direct evidence for thestrengthening and softening mechanisms in nano-twinning structured metals.
基金supported by the National Natural Science Foundation of China (51301011 and 11374029)Research Fund for the Doctoral Program of Higher Education of China (20131102120053)+5 种基金Fundamental Research Funds for the Central Universities (YWF-14-HHXY-013)Foundation for the Author of National Excellent Doctoral Dissertation of China (201214)Beijing Nova Program (Z121103002512017)Key Project of National Natural Science Foundation of China (11234011)Henry Fok of the Ministry of Education Fund (141008)Beijing City Board of Education Project (KM201310005009)