Effect of Si and Ti on dynamic recrystallization(DRX)of Cu-15Ni-8 Sn alloy was studied using hot compression tests over deformation temperature range of 750-950℃and strain rate range of 0.001-10 s^-1.The results show...Effect of Si and Ti on dynamic recrystallization(DRX)of Cu-15Ni-8 Sn alloy was studied using hot compression tests over deformation temperature range of 750-950℃and strain rate range of 0.001-10 s^-1.The results show that the dynamic recrystallization behavior during hot deformation is significantly affected by the trace elements of Si and Ti.The addition of Si and Ti promotes the formation of Ni16Si7Ti6 particles during hot deformation,which promotes the nucleation of dynamic recrystallization by accelerating the transition from low-angle boundaries(LABs)to high-angle boundaries(HABs).Ni16Si7Ti6 particles further inhibit the growth of recrystallized grains through the pinning effect.Based on the dynamic recrystallization behavior,a processing map of the alloy is built up to obtain the optimal processing parameters.Guided by the processing map,a hot-extruded Cu-15 Ni-8Sn alloy with a fine-grained microstructure is obtained,which shows excellent elongation of 30%and ultimate tensile strength of 910 MPa.展开更多
The 12 mm-thick Ti−6Al−4V(TC4)titanium alloy plates were welded using keyhole tungsten inert gas(K-TIG)welding at various heat inputs.The microstructure,grain boundary(GB)characteristics and mechanical properties of t...The 12 mm-thick Ti−6Al−4V(TC4)titanium alloy plates were welded using keyhole tungsten inert gas(K-TIG)welding at various heat inputs.The microstructure,grain boundary(GB)characteristics and mechanical properties of the weld metal zone(WMZ)were analyzed.The test results show that the K-TIG welds are well formed,and no obvious defects are observed when the heat input is 2.30−2.62 kJ/mm.When the heat input gradually increases,αlaths increase in length,andα′phase and residualβphase are reduced.The electron backscatter diffraction(EBSD)test results indicate that the high-angle GB proportion in the WMZ increases with the increase of heat input.The tensile strength of the WMZ gradually decreases and the elongation of the WMZ increases when the heat input increases from 2.30 to 2.62 kJ/mm.The impact toughness of the WMZ increases as the heat input increases.展开更多
To avoid the defects caused by the hydrogen evolution and improve the corrosion and wear properties of the electroplated films in the traditional aqueous bath electrodeposition,a supercritical carbon dioxide(Sc-CO2)em...To avoid the defects caused by the hydrogen evolution and improve the corrosion and wear properties of the electroplated films in the traditional aqueous bath electrodeposition,a supercritical carbon dioxide(Sc-CO2)emulsion was proposed to electrodeposite ternary nanocrystalline Co-Ni-P alloy films.Microstructure,corrosive and tribological properties of the Co-Ni-P films were investigated and compared with the ones electroplated by conventional method.The results show that the Co-Ni-P films produced with Sc-CO2assisted electrodeposition exhibit a more compact microstructure.The preferred orientation plane of hcp(110)for the Co-Ni-P films produced in conventional aqueous bath is changed to be hcp(100)for the one prepared in emulsified Sc-CO2bath.The microhardness,corrosion resistance and tribological properties of the Co-Ni-P films are substantially improved with the assistance of Sc-CO2in the electrodeposition bath.展开更多
The differences in the microstructure and elevated temperature tensile properties of gravity die cast,squeeze cast,and semi-solid thixoformed Al-Si-Cu-Mn-Fe alloys after thermal exposure at 300℃were discussed.The res...The differences in the microstructure and elevated temperature tensile properties of gravity die cast,squeeze cast,and semi-solid thixoformed Al-Si-Cu-Mn-Fe alloys after thermal exposure at 300℃were discussed.The results demonstrate that the elevated temperature tensile properties of semi-solid thixoformed alloys were significantly higher than those of gravity die cast and squeeze cast alloys,especially after thermal exposure for 100 h.The ultimate tensile strength(UTS)of semi-solid thixoformed alloys after thermal exposure at 300℃for 0.5,10 and 100 h were 181,122 and 110 MPa,respectively.The UTS values of semi-solid thixoformed alloys were higher than those of heat resistant aluminum alloys used in commercial applications.The enhanced elevated temperature tensile properties of semi-solid thixoformed experimental alloys after thermal exposure can be attributed to the combined reinforcement of precipitation strengthening and grain boundary strengthening due to thermally stable intermetallic phases as well as suitable grain size.展开更多
The effect of Si content on the microstructures and mechanical properties of the heat-treated Al-6.5 Cu-0.6 Mn-0.5 Fe alloy was investigated using image analysis,scanning electron microscopy(SEM),transmission electron...The effect of Si content on the microstructures and mechanical properties of the heat-treated Al-6.5 Cu-0.6 Mn-0.5 Fe alloy was investigated using image analysis,scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile testing.The results show that the mechanical properties of Al-6.5 Cu-0.6 Mn-0.5 Fe alloys decrease slightly when the Si content is below 1.0%.This can be attributed to the comprehensive effect of microstructure evolution,including the increase of nano-sized α-Fe,the coarsened grain size,and an increase in Al2 Cu content at the grain boundary.When the Si content is 1.5%,the mechanical properties of the Al-6.5 Cu-0.6 Mn-0.5 Fe alloys decrease significantly,and this can be attributed to the agglomerated second intermetallics,which is resulted from the formation of excess Si particles.展开更多
A facile method was proposed to prepare stretchable silver-based composite coatings with excellent conductivity and stability for flexible electronics.Silver coating was firstly deposited on thermoplastic polyurethane...A facile method was proposed to prepare stretchable silver-based composite coatings with excellent conductivity and stability for flexible electronics.Silver coating was firstly deposited on thermoplastic polyurethane(TPU)elastomer rubber surface via two-component spraying technique,then the superhydrophobic surface was obtained by one-step electrodeposition of cerium compounds(CeM)and graphene nanosheets(GNS)to produce Ag/CeM/GNS composite coatings.The obtained Ag/CeM/GNS composite coatings maintained high conductivity after experiencing bending cycles and stretching cycles.Furthermore,the as-prepared Ag/CeM/GNS composite coatings showed excellent self-cleaning and anti-fouling properties,and the corrosion resistance has improved significantly compared to the original Ag coating.In addition,the Ag/CeM/GNS composite coatings could drive the circuit normally in the states of tensile,bending and twisting deformation,showing excellent mechanical stability and applicability.As a result,it is believed that the prepared Ag/CeM/GNS composite coatings with excellent conductivity and stability have promising applications for flexible electronics in harsh conditions.展开更多
基金Project(2015A030312003) supported by the Guangdong Natural Science Foundation for Research Team,China
文摘Effect of Si and Ti on dynamic recrystallization(DRX)of Cu-15Ni-8 Sn alloy was studied using hot compression tests over deformation temperature range of 750-950℃and strain rate range of 0.001-10 s^-1.The results show that the dynamic recrystallization behavior during hot deformation is significantly affected by the trace elements of Si and Ti.The addition of Si and Ti promotes the formation of Ni16Si7Ti6 particles during hot deformation,which promotes the nucleation of dynamic recrystallization by accelerating the transition from low-angle boundaries(LABs)to high-angle boundaries(HABs).Ni16Si7Ti6 particles further inhibit the growth of recrystallized grains through the pinning effect.Based on the dynamic recrystallization behavior,a processing map of the alloy is built up to obtain the optimal processing parameters.Guided by the processing map,a hot-extruded Cu-15 Ni-8Sn alloy with a fine-grained microstructure is obtained,which shows excellent elongation of 30%and ultimate tensile strength of 910 MPa.
基金The authors are grateful for the financial supports from the Key Research and Development Program of Guangdong Province,China(2020B090928003)the Natural Science Foundation of Guangdong Province,China(2020A1515011050)+1 种基金the Science and Technology Base and Talent Special Project of Guangxi Province,China(AD19245150)Guangxi University of Science and Technology Doctoral Fund,China(19Z27).
文摘The 12 mm-thick Ti−6Al−4V(TC4)titanium alloy plates were welded using keyhole tungsten inert gas(K-TIG)welding at various heat inputs.The microstructure,grain boundary(GB)characteristics and mechanical properties of the weld metal zone(WMZ)were analyzed.The test results show that the K-TIG welds are well formed,and no obvious defects are observed when the heat input is 2.30−2.62 kJ/mm.When the heat input gradually increases,αlaths increase in length,andα′phase and residualβphase are reduced.The electron backscatter diffraction(EBSD)test results indicate that the high-angle GB proportion in the WMZ increases with the increase of heat input.The tensile strength of the WMZ gradually decreases and the elongation of the WMZ increases when the heat input increases from 2.30 to 2.62 kJ/mm.The impact toughness of the WMZ increases as the heat input increases.
基金Project (2015A030306026) supported by the Natural Science Funds for Distinguished Young Scholar of Guangdong Province,ChinaProject (51275176) supported by the National Natural Science Foundation of China+1 种基金Project (2016A010102009) supported by the Science and Technology Planning of Guangdong Province,ChinaProject (201707010055) supported by the Science and Technology Planning of Guangzhou City,China
文摘To avoid the defects caused by the hydrogen evolution and improve the corrosion and wear properties of the electroplated films in the traditional aqueous bath electrodeposition,a supercritical carbon dioxide(Sc-CO2)emulsion was proposed to electrodeposite ternary nanocrystalline Co-Ni-P alloy films.Microstructure,corrosive and tribological properties of the Co-Ni-P films were investigated and compared with the ones electroplated by conventional method.The results show that the Co-Ni-P films produced with Sc-CO2assisted electrodeposition exhibit a more compact microstructure.The preferred orientation plane of hcp(110)for the Co-Ni-P films produced in conventional aqueous bath is changed to be hcp(100)for the one prepared in emulsified Sc-CO2bath.The microhardness,corrosion resistance and tribological properties of the Co-Ni-P films are substantially improved with the assistance of Sc-CO2in the electrodeposition bath.
基金financially supported by the National Natural Science Foundation of China(Nos.51704084,52074131)the Science and Technology Plan of Guizhou Province,China(Nos.ZK2021(267),ZK2021(067))the Cultivation Project of Guizhou University,China(No.2019(23))。
文摘The differences in the microstructure and elevated temperature tensile properties of gravity die cast,squeeze cast,and semi-solid thixoformed Al-Si-Cu-Mn-Fe alloys after thermal exposure at 300℃were discussed.The results demonstrate that the elevated temperature tensile properties of semi-solid thixoformed alloys were significantly higher than those of gravity die cast and squeeze cast alloys,especially after thermal exposure for 100 h.The ultimate tensile strength(UTS)of semi-solid thixoformed alloys after thermal exposure at 300℃for 0.5,10 and 100 h were 181,122 and 110 MPa,respectively.The UTS values of semi-solid thixoformed alloys were higher than those of heat resistant aluminum alloys used in commercial applications.The enhanced elevated temperature tensile properties of semi-solid thixoformed experimental alloys after thermal exposure can be attributed to the combined reinforcement of precipitation strengthening and grain boundary strengthening due to thermally stable intermetallic phases as well as suitable grain size.
基金Projects(51704084,51605106) supported by the National Natural Science Foundation of ChinaProject(2017M623068) supported by China Postdoctoral Science Foundation+3 种基金Project(2015A030312003) supported by the Natural Science Foundation for Team Research of Guangdong Province,ChinaProject(JC(2016)1026)) supported by the Science and Technology Foundation of Guizhou Province of ChinaProject(KY(2017)101)) supported by the Young Talent Growth Foundation of Education Department of Guizhou Province of ChinaProject(RC2017(5788)) supported by the Science and Technology Plan of Guizhou Province of China
文摘The effect of Si content on the microstructures and mechanical properties of the heat-treated Al-6.5 Cu-0.6 Mn-0.5 Fe alloy was investigated using image analysis,scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile testing.The results show that the mechanical properties of Al-6.5 Cu-0.6 Mn-0.5 Fe alloys decrease slightly when the Si content is below 1.0%.This can be attributed to the comprehensive effect of microstructure evolution,including the increase of nano-sized α-Fe,the coarsened grain size,and an increase in Al2 Cu content at the grain boundary.When the Si content is 1.5%,the mechanical properties of the Al-6.5 Cu-0.6 Mn-0.5 Fe alloys decrease significantly,and this can be attributed to the agglomerated second intermetallics,which is resulted from the formation of excess Si particles.
基金support from the National Natural Science Foundation of China(No.52105186)the Guangdong Basic and Applied Basic Research Foundation,China(Nos.2019A1515011282,2022A1515011547,2021B1515120014)the Fangchenggang Scientific Research and Technology Development Project,China(No.AB21014008).
文摘A facile method was proposed to prepare stretchable silver-based composite coatings with excellent conductivity and stability for flexible electronics.Silver coating was firstly deposited on thermoplastic polyurethane(TPU)elastomer rubber surface via two-component spraying technique,then the superhydrophobic surface was obtained by one-step electrodeposition of cerium compounds(CeM)and graphene nanosheets(GNS)to produce Ag/CeM/GNS composite coatings.The obtained Ag/CeM/GNS composite coatings maintained high conductivity after experiencing bending cycles and stretching cycles.Furthermore,the as-prepared Ag/CeM/GNS composite coatings showed excellent self-cleaning and anti-fouling properties,and the corrosion resistance has improved significantly compared to the original Ag coating.In addition,the Ag/CeM/GNS composite coatings could drive the circuit normally in the states of tensile,bending and twisting deformation,showing excellent mechanical stability and applicability.As a result,it is believed that the prepared Ag/CeM/GNS composite coatings with excellent conductivity and stability have promising applications for flexible electronics in harsh conditions.
