Radiation-induced helium bubbles are detrimental to the mechanical properties of metals, usually causing severe hardening and embrittlement. Hexagonal close-packed(HCP) α-Zr alloys are one of the primary structural m...Radiation-induced helium bubbles are detrimental to the mechanical properties of metals, usually causing severe hardening and embrittlement. Hexagonal close-packed(HCP) α-Zr alloys are one of the primary structural materials for nuclear applications, however, the effect of helium bubbles on their deformation and fracture behaviors still remains unexplored. Here, we found that ordered helium bubbles prefer to align along the basal plane in HCP α-Zr. Micro-scale in situ tensile tests revealed that helium bubbles less than 8 nm in size can increase the critical resolved shear stress of the prismatic slip. However, once the helium bubbles are larger than 8 nm, a bubble-softening effect happens due to a decrease in number density of helium bubbles and an increase in porosity. Once the Schmid factor of basal slip is considerably higher than prismatic slip, bubble coalescence along the basal plane becomes the major failure mode in helium-irradiated α-Zr.展开更多
An AA3003 aluminum alloy prepared by twin-roll casting was modified by a small amount of zirconium. Annealing at 450 °C led to precipitation of coherent Al3Zr phase and a simultaneous co-precipitation of Mn-rich...An AA3003 aluminum alloy prepared by twin-roll casting was modified by a small amount of zirconium. Annealing at 450 °C led to precipitation of coherent Al3Zr phase and a simultaneous co-precipitation of Mn-richα-Al(Mn,Fe)Si phase. Severe plastic deformation by equal channel angular pressing resulted in the grain refinement and increase of microhardness. Observation by electron back-scatter diffraction and in-situ transmission electron microscopy revealed influence of pre-annealing on microstructure changes during post-deformation heat treatment. Dislocation recovery and precipitation ofα-Al(Mn,Fe)Si particles preceded recrystallization at 450 °C in material which was not annealed before deformation. The pre-deformation annealing enabled dynamic recovery during deformation as it depleted the solid solution from Mn atoms. Recrystallization was enhanced by Al3Zr precipitates.展开更多
基金supported financially by the National Key Research and Development Program of China (No. 2017YFB0702301)the National Natural Science Foundation of China (Nos. 51471128 and 51621063)+1 种基金the Innovation Project of Shannxi Province (No. 2017KTPT-12)111 Project of China (No. BP2018008)
文摘Radiation-induced helium bubbles are detrimental to the mechanical properties of metals, usually causing severe hardening and embrittlement. Hexagonal close-packed(HCP) α-Zr alloys are one of the primary structural materials for nuclear applications, however, the effect of helium bubbles on their deformation and fracture behaviors still remains unexplored. Here, we found that ordered helium bubbles prefer to align along the basal plane in HCP α-Zr. Micro-scale in situ tensile tests revealed that helium bubbles less than 8 nm in size can increase the critical resolved shear stress of the prismatic slip. However, once the helium bubbles are larger than 8 nm, a bubble-softening effect happens due to a decrease in number density of helium bubbles and an increase in porosity. Once the Schmid factor of basal slip is considerably higher than prismatic slip, bubble coalescence along the basal plane becomes the major failure mode in helium-irradiated α-Zr.
基金The financial supports of grants GACR P107-12-0921 and SVV-2015-260213
文摘An AA3003 aluminum alloy prepared by twin-roll casting was modified by a small amount of zirconium. Annealing at 450 °C led to precipitation of coherent Al3Zr phase and a simultaneous co-precipitation of Mn-richα-Al(Mn,Fe)Si phase. Severe plastic deformation by equal channel angular pressing resulted in the grain refinement and increase of microhardness. Observation by electron back-scatter diffraction and in-situ transmission electron microscopy revealed influence of pre-annealing on microstructure changes during post-deformation heat treatment. Dislocation recovery and precipitation ofα-Al(Mn,Fe)Si particles preceded recrystallization at 450 °C in material which was not annealed before deformation. The pre-deformation annealing enabled dynamic recovery during deformation as it depleted the solid solution from Mn atoms. Recrystallization was enhanced by Al3Zr precipitates.
