The general corrosion and environmental cracking resistances of Al-Cu-Li alloy AA2195 were investigated in 3.5% NaCl environment and compared with those of another high strength alloy AA2219. The general corrosion re...The general corrosion and environmental cracking resistances of Al-Cu-Li alloy AA2195 were investigated in 3.5% NaCl environment and compared with those of another high strength alloy AA2219. The general corrosion resistance of these alloys was examined using immersion corrosion and potentiodynamic polarization tests, while the stress corrosion cracking （SCC） resistance was evaluated by slow strain rate test （SSRT） method. The tested samples were further characterized by SEM-EDS and optical profilometry to study the change in corrosion morphology, elemental content and depth of corrosion attack. The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of the alloys. The results indicated that the corrosion resistance of AA2195 alloy was better than that of AA2219 alloy as it exhibited lower corrosion rate, along with lower pit depth and density. However, the SCC index （εNaCl/εair） measured was greater than 0.90, indicating good environmental cracking resistance of both the alloys. Detailed fractography of the failed samples under SEM？EDS, in general, revealed a typical ductile cracking morphology for both the alloys.展开更多
We propose a novel metamaterial structure operating at the terahertz band. This structure is assembled by a split ring resonator (SRR) with a metal mesh within a unit cell. Our experimental studies on the composite st...We propose a novel metamaterial structure operating at the terahertz band. This structure is assembled by a split ring resonator (SRR) with a metal mesh within a unit cell. Our experimental studies on the composite structure indicate that the coupling of the SRR and metal mesh significantly contribute to the transparency at the terahertz range. Moreover, we experimentally demonstrated the verity of transmission peak of this structure by changing the relative positions of the SRR and the metal mesh. The simulated electric field redistributions support the dependence between position of the two components and the transmission response. This study is the first to report a hybrid metamaterial structure consisting of an SRR array and a metal mesh within a unit cell. The designed process and resonance characteristics of this composite structure make it an excellent candidate for developing tunable terahertz components via integration with the MEMS (Micro Electronic Mechanical System) technology.展开更多
文摘The general corrosion and environmental cracking resistances of Al-Cu-Li alloy AA2195 were investigated in 3.5% NaCl environment and compared with those of another high strength alloy AA2219. The general corrosion resistance of these alloys was examined using immersion corrosion and potentiodynamic polarization tests, while the stress corrosion cracking （SCC） resistance was evaluated by slow strain rate test （SSRT） method. The tested samples were further characterized by SEM-EDS and optical profilometry to study the change in corrosion morphology, elemental content and depth of corrosion attack. The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of the alloys. The results indicated that the corrosion resistance of AA2195 alloy was better than that of AA2219 alloy as it exhibited lower corrosion rate, along with lower pit depth and density. However, the SCC index （εNaCl/εair） measured was greater than 0.90, indicating good environmental cracking resistance of both the alloys. Detailed fractography of the failed samples under SEM？EDS, in general, revealed a typical ductile cracking morphology for both the alloys.
基金supported by the Program of "One Hundred Talented People" of the Chinese Academy of Sciences and the Organization Department of Sichuanthe National Natural Science Foundation of China (Grant No.11176033)the Natural Science Foundation of Beijing (Grant No.4102016)
文摘We propose a novel metamaterial structure operating at the terahertz band. This structure is assembled by a split ring resonator (SRR) with a metal mesh within a unit cell. Our experimental studies on the composite structure indicate that the coupling of the SRR and metal mesh significantly contribute to the transparency at the terahertz range. Moreover, we experimentally demonstrated the verity of transmission peak of this structure by changing the relative positions of the SRR and the metal mesh. The simulated electric field redistributions support the dependence between position of the two components and the transmission response. This study is the first to report a hybrid metamaterial structure consisting of an SRR array and a metal mesh within a unit cell. The designed process and resonance characteristics of this composite structure make it an excellent candidate for developing tunable terahertz components via integration with the MEMS (Micro Electronic Mechanical System) technology.
