The aim of present work is to develop a crystal plasticity modeling approach to integrate slip,dynamic recrystallization(DRX)and grain boundary sliding(GBS)for simulating the deformation behavior and texture evolution...The aim of present work is to develop a crystal plasticity modeling approach to integrate slip,dynamic recrystallization(DRX)and grain boundary sliding(GBS)for simulating the deformation behavior and texture evolution of magnesium alloys at high temperatures.Firstly,the deformation mechanisms of an AZ31B Mg alloy sheet at 300°C were investigated by examining texture and microstructure evolution during uniaxial tension and compression tests.DRX refines microstructure at strains less than 0.2,and subsequently GBS plays a significant role during deformation process.A GBS model is developed to evaluate strain and grain rotation induced by GBS,and implemented into the polycrystal plasticity framework VPSC.The VPSC-DRX-GBS model can well reproduce the stress−strain curves,grain size,texture evolution and significant texture differences in tension and compression tests due to GBS.The calculated GBS contribution ratio in tension is obviously higher than that in compression due to easier cavity nucleation at grain boundaries under tension loading.展开更多
The commercialization of proton exchange membrane fuel cells(PEMFCs)could provide a cleaner energy society in the near future.However,the sluggish reaction kinetics and harsh conditions of the oxygen reduction reactio...The commercialization of proton exchange membrane fuel cells(PEMFCs)could provide a cleaner energy society in the near future.However,the sluggish reaction kinetics and harsh conditions of the oxygen reduction reaction affect the durability and cost of PEMFCs.Most previous reports on Pt-based electrocatalyst designs have focused more on improving their activity;however,with the commercialization of PEMFCs,durability has received increasing attention.In-depth insight into the structural evolution of Pt-based electrocatalysts throughout their lifecycle can contribute to further optimization of their activity and durability.The development of in situ electron microscopy and other in situ techniques has promoted the elucidation of the evolution mechanism.This mini review highlights recent advances in the structural evolution of Pt-based electrocatalysts.The mechanisms are adequately discussed,and some methods to inhibit or exploit the structural evolution of the catalysts are also briefly reviewed.展开更多
基金supported by the National Natural Science Foundation of China(21073119,21173146,21473112)National Basic Research Program of China(973)(2014CB239702)~~
基金The authors would like to acknowledge the support from the National Natural Science Foundation of China(51675331 and 51775337)Major Projects of the Ministry of Education(311017)Pei-dong WU would like to acknowledge the support from the Natural Sciences and Engineering Research Council of Canada(NSERC,RGPIN-2016-06464).
文摘The aim of present work is to develop a crystal plasticity modeling approach to integrate slip,dynamic recrystallization(DRX)and grain boundary sliding(GBS)for simulating the deformation behavior and texture evolution of magnesium alloys at high temperatures.Firstly,the deformation mechanisms of an AZ31B Mg alloy sheet at 300°C were investigated by examining texture and microstructure evolution during uniaxial tension and compression tests.DRX refines microstructure at strains less than 0.2,and subsequently GBS plays a significant role during deformation process.A GBS model is developed to evaluate strain and grain rotation induced by GBS,and implemented into the polycrystal plasticity framework VPSC.The VPSC-DRX-GBS model can well reproduce the stress−strain curves,grain size,texture evolution and significant texture differences in tension and compression tests due to GBS.The calculated GBS contribution ratio in tension is obviously higher than that in compression due to easier cavity nucleation at grain boundaries under tension loading.
文摘The commercialization of proton exchange membrane fuel cells(PEMFCs)could provide a cleaner energy society in the near future.However,the sluggish reaction kinetics and harsh conditions of the oxygen reduction reaction affect the durability and cost of PEMFCs.Most previous reports on Pt-based electrocatalyst designs have focused more on improving their activity;however,with the commercialization of PEMFCs,durability has received increasing attention.In-depth insight into the structural evolution of Pt-based electrocatalysts throughout their lifecycle can contribute to further optimization of their activity and durability.The development of in situ electron microscopy and other in situ techniques has promoted the elucidation of the evolution mechanism.This mini review highlights recent advances in the structural evolution of Pt-based electrocatalysts.The mechanisms are adequately discussed,and some methods to inhibit or exploit the structural evolution of the catalysts are also briefly reviewed.
