A retrogression process was applied to AA7075alloy at180,240and320°C for1,30,50,70,90and120min.After the retrogression,aging treatment was reapplied with T6conditions(120°C,24h).The mechanical properties of ...A retrogression process was applied to AA7075alloy at180,240and320°C for1,30,50,70,90and120min.After the retrogression,aging treatment was reapplied with T6conditions(120°C,24h).The mechanical properties of aged samples were determined by V-Charpy and hardness tests and also,physical properties of samples were determined by electrical conductivity tests.Moreover,microstructural properties were characterized by light microscope and transmission electron microscope.The results show that the effects of the temperature and the duration of the retrogression and reagent on the impact toughness and hardness are related to the precipitates at the grain boundary.展开更多
Stress corrosion cracking (SCC) resistance of a spray formed Al-Zn-Mg-Cu alloy underwent retrogression and reaging (RRA) was studied by slow strain rate tests in dry air and 3.5 wt% NaCl solution. The results showed t...Stress corrosion cracking (SCC) resistance of a spray formed Al-Zn-Mg-Cu alloy underwent retrogression and reaging (RRA) was studied by slow strain rate tests in dry air and 3.5 wt% NaCl solution. The results showed that after RRA treatment, interrupted η phases at grain boundaries and slightly wide precipitate free zones could decrease SCC susceptibility of the alloy. Lots of reticular dislocations appeared in deformation process could prevent hydrogen induced cracking, and then SCC. Abundance transgranular dispersive η' phases separated out again promoted tensile strength to 759.4 MPa. The fracture ways of the specimens were dimple fracture in dry air and sub-cleavage fracture in 3.5% NaCl solution.展开更多
Al-based metal matrix composites [MMCs] have been the research interest of a wide spectrum of material scientists throughout the world for some over two decades now. The present paper has chosen one alloy system namel...Al-based metal matrix composites [MMCs] have been the research interest of a wide spectrum of material scientists throughout the world for some over two decades now. The present paper has chosen one alloy system namely the 7xxx series and from an extensive literature review concluded that since the beginning of the new millennium nothing note worthy has been added to the knowledge already gained in the last quarter of the last century except confirm the earlier findings that MMCs if properly fabricated by choosing the processing route and with appropriate size and volume fraction of dispersoids can improve most of the mechanical, corrosion and wear resistant properties of the base alloy. The author’s own research activities using this alloy system for making MMCs that include attempts to improve upon the properties by making composites, ageing and also secondary processing have been included. An attempt has been made to establish the stretch to which improvement is possible in the alloy system by making composites and trying all other routes known for meaningful improvement in properties. Further, the way forward for such particulate composites has been drawn to realise the material scientists’ dream of seeing such MMCs as engineering components. For this, the areas which now need research include mass production of composites, focus on its machining, joining, processing as also reduction in the size of dispersoids are some of the areas that have been identified and discussed in the paper.展开更多
基金supported by Yildiz Technical University Scientific Research Project Unit under Contract No:2016-07-02-DOP02
文摘A retrogression process was applied to AA7075alloy at180,240and320°C for1,30,50,70,90and120min.After the retrogression,aging treatment was reapplied with T6conditions(120°C,24h).The mechanical properties of aged samples were determined by V-Charpy and hardness tests and also,physical properties of samples were determined by electrical conductivity tests.Moreover,microstructural properties were characterized by light microscope and transmission electron microscope.The results show that the effects of the temperature and the duration of the retrogression and reagent on the impact toughness and hardness are related to the precipitates at the grain boundary.
文摘Stress corrosion cracking (SCC) resistance of a spray formed Al-Zn-Mg-Cu alloy underwent retrogression and reaging (RRA) was studied by slow strain rate tests in dry air and 3.5 wt% NaCl solution. The results showed that after RRA treatment, interrupted η phases at grain boundaries and slightly wide precipitate free zones could decrease SCC susceptibility of the alloy. Lots of reticular dislocations appeared in deformation process could prevent hydrogen induced cracking, and then SCC. Abundance transgranular dispersive η' phases separated out again promoted tensile strength to 759.4 MPa. The fracture ways of the specimens were dimple fracture in dry air and sub-cleavage fracture in 3.5% NaCl solution.
文摘Al-based metal matrix composites [MMCs] have been the research interest of a wide spectrum of material scientists throughout the world for some over two decades now. The present paper has chosen one alloy system namely the 7xxx series and from an extensive literature review concluded that since the beginning of the new millennium nothing note worthy has been added to the knowledge already gained in the last quarter of the last century except confirm the earlier findings that MMCs if properly fabricated by choosing the processing route and with appropriate size and volume fraction of dispersoids can improve most of the mechanical, corrosion and wear resistant properties of the base alloy. The author’s own research activities using this alloy system for making MMCs that include attempts to improve upon the properties by making composites, ageing and also secondary processing have been included. An attempt has been made to establish the stretch to which improvement is possible in the alloy system by making composites and trying all other routes known for meaningful improvement in properties. Further, the way forward for such particulate composites has been drawn to realise the material scientists’ dream of seeing such MMCs as engineering components. For this, the areas which now need research include mass production of composites, focus on its machining, joining, processing as also reduction in the size of dispersoids are some of the areas that have been identified and discussed in the paper.
