The primary radiation damage in pure V and TiVTa concentrated solid-solution alloy(CSA)was studied using a molecular dynamics method.We have performed displacement cascade simulations to explore the generation and evo...The primary radiation damage in pure V and TiVTa concentrated solid-solution alloy(CSA)was studied using a molecular dynamics method.We have performed displacement cascade simulations to explore the generation and evolution behavior of irradiation defects.The results demonstrate that the defect accumulation and agglomeration in TiVTa CSA are significantly suppressed compared to pure V.The peak value of Frenkel pairs during cascade collisions in TiVTa CSA is much higher than that in pure V due to the lower formation energy of point defects.Meanwhile,the longer lifetime of the thermal spike relaxation and slow energy dissipation capability of TiVTa CSA can facilitate the recombination of point defects.The defect agglomeration rate in TiVTa CSA is much lower due to the lower binding energy of interstitial clusters and reduced interstitial diffusivity.Furthermore,the occurrence probability of dislocation loops in TiVTa CSA is lower than that in pure V.The reduction in primary radiation damage may enhance the radiation resistance of TiVTa CSA,and the improved radiation tolerance is primarily attributed to the relaxation stage and long-term defect evolution rather than the ballistic stage.These results can provide fundamental insights into irradiation-induced defects evolution in refractory CSAs.展开更多
The sensitivity analysis functions on globularized fraction ofαlamellae were established using a physically-based microstructure model and gradient method.These functions were applied to the sensitivity analysis on g...The sensitivity analysis functions on globularized fraction ofαlamellae were established using a physically-based microstructure model and gradient method.These functions were applied to the sensitivity analysis on globularized fraction ofαlamellae in TC17 alloy.The material constants in these functions are determined using the genetic algorithm-based objective optimization technique.The globularized fraction ofαlamellae during isothermal compression of TC17 alloy was quantitatively analyzed based on scanning electron microscopy(SEM)observation.The results show thatαlamellae mostly change to equiaxedαgrains at a deformation temperature of 1083 K,a strain rate of 0.01 s^-1 and a strain of 1.2.The globularized fraction decreases with increasing strain rate because lower strain rate provides enough time for the spheroidization.The effect of deformation temperature on the globularized fraction is controlled by the strain rate.And,the predicted derivations of globularized fraction with respect to processing parameters show good agreement with the experimental values.展开更多
Contact electrification(CE)is a pretty common phenomenon,but still is poorly understood.The long-standing controversy over the mechanisms of CE related to polymers is particularly intense due to their complexity.In th...Contact electrification(CE)is a pretty common phenomenon,but still is poorly understood.The long-standing controversy over the mechanisms of CE related to polymers is particularly intense due to their complexity.In this paper,the CE between metals and polymers is systematically studied,which shows the evolution of surfaces is accompanied by variations of CE outputs.The variations of CE charge quantity are closely related to the creep and deformation of the polymer and metal surfaces.Then the relationship between CE and polymer structures is put forward,which is essentially determined by the electronegativity of elements and the functional groups in the polymers.The effects of load and contact frequency on the CE process and outputs are also investigated,indicating the increase of CE charge quantity with load and frequency.Material transfer from polymer to metal is observed during CE while electrons transfer from metal to polymer,both of which are believed to have an influence on each other.The findings advance our understanding of the mechanism of CE between metal and polymers,and provides insights into the performance of CE-based application in various conditions,which sheds light on the design and optimization of CE-based energy harvest and self-powered sensing devices.展开更多
Adiabatic shear band (ASB) was narrow region where softening occurred and concentrated plastic defor- mation took place. In present study, the effects of height reduction and deformation temperature on ASB were inve...Adiabatic shear band (ASB) was narrow region where softening occurred and concentrated plastic defor- mation took place. In present study, the effects of height reduction and deformation temperature on ASB were investigated by means of optical microscopy (OM) and scanning electron microscopy (SEM). And the deformation mechanisms within the shear band were discussed thor- oughly with the help of transmission electron microscopy (TEM). There is a critical strain for the formation of ASB during warm compression of Ti-6AI-4V alloy. The width of ASB increases with height reduction increasing. Elon- gated alpha grains within shear band grow up with defor- mation temperature increasing. Some ultrafine grains that confirm the occurrence of dynamic recrystallization are observed within shear band during warm compression of Ti-6AI-4V alloy.展开更多
基金Project supported by the Dean’s Fund of China Institute of Atomic Energy(Grant No.219256)the CNNC Science Fund for Talented Young Scholars.
文摘The primary radiation damage in pure V and TiVTa concentrated solid-solution alloy(CSA)was studied using a molecular dynamics method.We have performed displacement cascade simulations to explore the generation and evolution behavior of irradiation defects.The results demonstrate that the defect accumulation and agglomeration in TiVTa CSA are significantly suppressed compared to pure V.The peak value of Frenkel pairs during cascade collisions in TiVTa CSA is much higher than that in pure V due to the lower formation energy of point defects.Meanwhile,the longer lifetime of the thermal spike relaxation and slow energy dissipation capability of TiVTa CSA can facilitate the recombination of point defects.The defect agglomeration rate in TiVTa CSA is much lower due to the lower binding energy of interstitial clusters and reduced interstitial diffusivity.Furthermore,the occurrence probability of dislocation loops in TiVTa CSA is lower than that in pure V.The reduction in primary radiation damage may enhance the radiation resistance of TiVTa CSA,and the improved radiation tolerance is primarily attributed to the relaxation stage and long-term defect evolution rather than the ballistic stage.These results can provide fundamental insights into irradiation-induced defects evolution in refractory CSAs.
基金Project(51575446) supported by the National Natural Science Foundation of ChinaProject(2016JQ5070) supported by the Natural Science Basis Research Plan of Shaanxi Province,China+1 种基金Project(2017KJXX-27) supported by the Youth Science and Technology New Star Plan of Shaanxi Province,ChinaProject(3102017AX003) supported by the Fundamental Research Funds for the Central Universities,China
文摘The sensitivity analysis functions on globularized fraction ofαlamellae were established using a physically-based microstructure model and gradient method.These functions were applied to the sensitivity analysis on globularized fraction ofαlamellae in TC17 alloy.The material constants in these functions are determined using the genetic algorithm-based objective optimization technique.The globularized fraction ofαlamellae during isothermal compression of TC17 alloy was quantitatively analyzed based on scanning electron microscopy(SEM)observation.The results show thatαlamellae mostly change to equiaxedαgrains at a deformation temperature of 1083 K,a strain rate of 0.01 s^-1 and a strain of 1.2.The globularized fraction decreases with increasing strain rate because lower strain rate provides enough time for the spheroidization.The effect of deformation temperature on the globularized fraction is controlled by the strain rate.And,the predicted derivations of globularized fraction with respect to processing parameters show good agreement with the experimental values.
基金supported by the National Natural Science Foundation of China(Grant Nos.52075249,51505217,51435008,and 51705247)。
文摘Contact electrification(CE)is a pretty common phenomenon,but still is poorly understood.The long-standing controversy over the mechanisms of CE related to polymers is particularly intense due to their complexity.In this paper,the CE between metals and polymers is systematically studied,which shows the evolution of surfaces is accompanied by variations of CE outputs.The variations of CE charge quantity are closely related to the creep and deformation of the polymer and metal surfaces.Then the relationship between CE and polymer structures is put forward,which is essentially determined by the electronegativity of elements and the functional groups in the polymers.The effects of load and contact frequency on the CE process and outputs are also investigated,indicating the increase of CE charge quantity with load and frequency.Material transfer from polymer to metal is observed during CE while electrons transfer from metal to polymer,both of which are believed to have an influence on each other.The findings advance our understanding of the mechanism of CE between metal and polymers,and provides insights into the performance of CE-based application in various conditions,which sheds light on the design and optimization of CE-based energy harvest and self-powered sensing devices.
基金financially supported by the National Natural Science Foundation of China(No.51575446)the Fundamental Research Funds for the Central Universities(No.3102014JCQ01016)
文摘Adiabatic shear band (ASB) was narrow region where softening occurred and concentrated plastic defor- mation took place. In present study, the effects of height reduction and deformation temperature on ASB were investigated by means of optical microscopy (OM) and scanning electron microscopy (SEM). And the deformation mechanisms within the shear band were discussed thor- oughly with the help of transmission electron microscopy (TEM). There is a critical strain for the formation of ASB during warm compression of Ti-6AI-4V alloy. The width of ASB increases with height reduction increasing. Elon- gated alpha grains within shear band grow up with defor- mation temperature increasing. Some ultrafine grains that confirm the occurrence of dynamic recrystallization are observed within shear band during warm compression of Ti-6AI-4V alloy.