High temperature pre-precipitation （HTPP）took place in7005 alloy at various temperatures after solution treatment and itsinfluence on mechanical properties, corrosion behaviors and microstructure of the alloy was in...High temperature pre-precipitation （HTPP）took place in7005 alloy at various temperatures after solution treatment and itsinfluence on mechanical properties, corrosion behaviors and microstructure of the alloy was investigated using tensile test, intergranular corrosion （IGC） test, slow strain rate testing （SSRT）, together with microstructural examinations. It is found that Vickers hardness of the aged alloy decreases gradually with decreasing the HTPP temperature, and almost a reverse trend of electrical conductivity is found compared to the hardness changes. Depending on the changes, two HTPP temperaturesof 440 and 420℃ were chosen for comparative study. Results reveal that HTPP alloy tempers exhibit higher resistance to stress corrosion cracking （SCC） and IGC than none pre-precipitate one with an acceptable strength loss due to the substantial enhancement of distribution discontinuity of the coarse grain boundary precipitates （GBPs）, and the coarsening and interspacing effect on GBPs becomes more obvious with decreasing the pre-precipitation temperature.展开更多
The correlations among the corrosion behaviour,grain-boundary microchemistry,and Zn content in Al-Zn-Mg-Cu alloys were studied using stress corrosion cracking(SCC)and intergranular corrosion(IGC)tests,combined with sc...The correlations among the corrosion behaviour,grain-boundary microchemistry,and Zn content in Al-Zn-Mg-Cu alloys were studied using stress corrosion cracking(SCC)and intergranular corrosion(IGC)tests,combined with scanning electron microscopy(SEM)and high-angle angular dark field scanning transmission electron microscopy(HAADF-STEM)microstructural examinations.The results showed that the tensile strength enhancement of high Zn-containing Al-Zn-Mg-Cu alloys was mainly attributed to the high density nano-scale matrix precipitates.The SCC plateau velocity for the alloy with 11.0 wt.%Zn was about an order of magnitude greater than that of the alloy with 7.9 wt.%Zn,which was mainly associated with Zn enrichment in grain boundary precipitates and wide precipitates-free zones.The SCC mechanisms of different Zn-containing alloys were discussed based on fracture features,grain-boundary microchemistry,and electrochemical properties.展开更多
基金Project(51301209)supported by the National Natural Science Foundation of China
文摘High temperature pre-precipitation （HTPP）took place in7005 alloy at various temperatures after solution treatment and itsinfluence on mechanical properties, corrosion behaviors and microstructure of the alloy was investigated using tensile test, intergranular corrosion （IGC） test, slow strain rate testing （SSRT）, together with microstructural examinations. It is found that Vickers hardness of the aged alloy decreases gradually with decreasing the HTPP temperature, and almost a reverse trend of electrical conductivity is found compared to the hardness changes. Depending on the changes, two HTPP temperaturesof 440 and 420℃ were chosen for comparative study. Results reveal that HTPP alloy tempers exhibit higher resistance to stress corrosion cracking （SCC） and IGC than none pre-precipitate one with an acceptable strength loss due to the substantial enhancement of distribution discontinuity of the coarse grain boundary precipitates （GBPs）, and the coarsening and interspacing effect on GBPs becomes more obvious with decreasing the pre-precipitation temperature.
基金financial supports from the National Key Research and Development Program of China(No.2016-YFB0300801)the State Key Laboratory of High Performance Complex Manufacturing of Central South University,China(No.ZZYJKT2020-03)the National Key Laboratory of Science and Technology for National Defence on High-strength Lightweight Structural Materials of China(No.20190104)。
文摘The correlations among the corrosion behaviour,grain-boundary microchemistry,and Zn content in Al-Zn-Mg-Cu alloys were studied using stress corrosion cracking(SCC)and intergranular corrosion(IGC)tests,combined with scanning electron microscopy(SEM)and high-angle angular dark field scanning transmission electron microscopy(HAADF-STEM)microstructural examinations.The results showed that the tensile strength enhancement of high Zn-containing Al-Zn-Mg-Cu alloys was mainly attributed to the high density nano-scale matrix precipitates.The SCC plateau velocity for the alloy with 11.0 wt.%Zn was about an order of magnitude greater than that of the alloy with 7.9 wt.%Zn,which was mainly associated with Zn enrichment in grain boundary precipitates and wide precipitates-free zones.The SCC mechanisms of different Zn-containing alloys were discussed based on fracture features,grain-boundary microchemistry,and electrochemical properties.
