In this work,a new treatment method combining ultrasonic vibration with FeCoNiCrCu high entropy alloy(HEA)coating was used to prepared Al/Mg bimetal through the lost foam compound casting.The effects of composite trea...In this work,a new treatment method combining ultrasonic vibration with FeCoNiCrCu high entropy alloy(HEA)coating was used to prepared Al/Mg bimetal through the lost foam compound casting.The effects of composite treatment involving ultrasonic vibration and HEA coating on interfacial microstructure and mechanical properties of Al/Mg bimetal were studied.Results demonstrate that the interface thickness of the Al/Mg bimetal with composite treatment significantly decreases to only 26.99%of the thickness observed in the untreated Al/Mg bimetal.The HEA coating hinders the diffusion between Al and Mg,resulting the significant reduction in Al/Mg intermetallic compounds in the interface.The Al/Mg bimetal interface with composite treatment is composed of Al_(3)Mg_(2)and Mg_(2)Si/AlxFeCoNiCrCu+FeCoNiCrCu/δ-Mg+Al_(12)Mg_(17)eutectic structures.The interface resulting from the composite treatment has a lower hardness than that without treatment.The acoustic cavitation and acoustic streaming effects generated by ultrasonic vibration promote the diffusion of Al elements within the HEA coating,resulting in a significant improvement in the metallurgical bonding quality on the Mg side.The fracture position shifts from the Mg side of the Al/Mg bimetal only with HEA coating to the Al side with composite treatment.The shear strength of the Al/Mg bimetal increases from 32.16 MPa without treatment to 63.44 MPa with ultrasonic vibration and HEA coating,increasing by 97.26%.展开更多
A nickel-based coating was deposited on the pure Al substrate by immersion plating,and the Al/Cu bimetals were prepared by diffusion bonding in the temperature range of 450-550 ℃.The interce microstructure and fractu...A nickel-based coating was deposited on the pure Al substrate by immersion plating,and the Al/Cu bimetals were prepared by diffusion bonding in the temperature range of 450-550 ℃.The interce microstructure and fracture surface of Al/Cu joints were studied by scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The mechanical properties of the Al/Cu bimetals were measured by tensile shear and microhardness tests.The results show that the Ni interiayer can effectively eliminate the formation of Al-Cu intermetallic compounds.The Al/Ni interface consists of the Al3Ni and Al3Ni2 phases,while it is Ni-Cu solid solution at the Ni/Cu interce.The tensile shear strength of the joints is improved by the addition of Ni interiayer.The joint with Ni interiayer annealed at 500 ℃ exhibits a maximum value of tensile shear strength of 34.7 MPa.展开更多
Compound casting is an efficient method for bonding dissimilar metals,in which a dramatic reaction can occur between the melt and solid.The centrifugal casting process,a type of compound casting,was applied to cast Al...Compound casting is an efficient method for bonding dissimilar metals,in which a dramatic reaction can occur between the melt and solid.The centrifugal casting process,a type of compound casting,was applied to cast Al/Mg dissimilar bimetals.Magnesium melt was poured at 700 °C,with melt-to-solid volume ratios(Vm/Vs) of 1.5 and 3,into a preheated hollow aluminum cylinder.The preheating temperatures of the solid part were 320,400,and 450 °C,and the constant rotational speed was 1,600 rpm.The cast parts were kept inside the casting machine until reaching the cooling temperature of 150 °C.The result showed that an increase in preheating temperature from 320 to 450 °C led to an enhanced reaction layer thickness.In addition,an increase in the Vm/Vs from 1.5 to 3 resulted in raising the interface thickness from 1.2 to 1.8 mm.Moreover,the interface was not continuously formed when a Vm/Vs of 3 was selected.In this case,the force of contraction overcame the resultant acting force on the interface.An interface formed at the volume ratio of 1.5 was examined using scanning electron microscopy(SEM) equipped with energy-dispersive X-ray spectroscopy(EDS),and the results demonstrated the formation of Al_(3)Mg_(2),Al_(12)Mg_(17) and(δ+Al_(12)Mg_(17)) eutectic structures in the interface.展开更多
In this work,a vibration was applied in the preparation of the Mg/Al bimetal by a novel compound casting in order to improve the mechanical properties of the Mg/Al bimetal,and the effect of the vibration on the interf...In this work,a vibration was applied in the preparation of the Mg/Al bimetal by a novel compound casting in order to improve the mechanical properties of the Mg/Al bimetal,and the effect of the vibration on the interfacial microstructure and mechanical properties of the Mg/Al bimetal was investigated.The results indicated that the vibration had a significant effect on the interfacial microstructure and mechanical properties of the Mg/Al bimetal,but it did not change the phase compositions of the interface,which was composed of layerⅠ(Al3Mg2+Mg2Si),layerⅡ(Al_(12)Mg_(17)+Mg_(2)Si)and layerⅢ(Al_(12)Mg_(17)/δ-Mg).Without vibration,the Mg_(2)Si phase with a needle-like morphology mainly aggregated in the layerⅡof the interface.After the application of the vibration,the SEM and EBSD analysis results showed that the Mg_(2)Si and Al3Mg2phases in the interface were obviously refined,and the distribution of the Mg_(2)Si became more uniform,due to the strong forced convection of the molten metal resulting from the vibration.The TEM analysis indicated that the interface between the A_(l3)Mg_(2) and Mg_(2)Si phases was non-coherent,suggesting the Mg_(2)Si particles cannot act as a heterogeneous nucleation base during the solidification process of the interface.Compared to the Mg/Al bimetal without vibration,the shear strength of the Mg/Al bimetal with vibration increased by about 50%from 31.7 MPa on average to 47.5 MPa,and the hardness of the layer I of the interface increased,and the hardness of the layerⅢdecreased.The fracture surface transformed from a flat fracture morphology without vibration to an irregular zigzag fracture morphology.展开更多
In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HE...In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer.The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis.Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg,which is conducive to the formation of solid solution,especially when the thickness of HEA is 800 nm.With the increase of casting temperature from 720 ℃ to 730 ℃,740℃,and 750 ℃,α-Al(Mg),α-Al(Mg)+Al3Mg2,Al3Mg2+Al12Mg17,and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal,respectively.When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 ℃,the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.展开更多
Al/Mg bimetal was prepared by lost foam solid-liquid compound casting,and the effects of mechanical vibration on the filling and solidification behavior,microstructure and performance of the bimetal were investigated....Al/Mg bimetal was prepared by lost foam solid-liquid compound casting,and the effects of mechanical vibration on the filling and solidification behavior,microstructure and performance of the bimetal were investigated.Results show that the mechanical vibration has a remarkable influence on the filling and solidification processes.It is found that after mechanical vibration,the filling rate increases and the filling rate at different times is more uniform than that without vibration.In addition,the mechanical vibration also increases the wettability between liquid AZ91D and A356 inlays.The mechanical vibration reduces the horizontal and vertical temperature gradient of the casting and makes the temperature distribution of the whole casting more uniform.Compared to the Al/Mg bimetal without vibration,the shear strength is improved by 39.76%after the mechanical vibration is applied,due to the decrease of the inclusions and Al_(12)Mg_(17) dendrites,and the refinement and uniform distribution of the Mg_(2)Si particles in the interface of the Al/Mg bimetal.展开更多
[Objective] The research aimed to study reductive dechlorination effect of PCBs in groundwater by Fe/Zn bimetal. [Method] Fe/Zn bi- metal as reduction system, PCBs degradation ratio as inspected index, degradation eff...[Objective] The research aimed to study reductive dechlorination effect of PCBs in groundwater by Fe/Zn bimetal. [Method] Fe/Zn bi- metal as reduction system, PCBs degradation ratio as inspected index, degradation effect of PCBs by Fe/Zn bimetallic system when adding self- made hydroxypropyl-β-cyclodextdn （HP-β-CD） was studied. Meanwhile, we investigated the influences of loading ratio and Fe-Zn dosage on PCBs dechlorination. [ Result] PCBs was significantly solubilized by the synthesized HP-β-CD. With increase of the HP-β-CD concentration, the apparent solubility of PCBs increased linearly, forming 1：1 inclusion complex. When Fe-Zn dosage was 10 g, and mass fraction of Zn was 7%, the dechlori- nation efficiency of 321 μg/L PCBs was 47.6% after degrading for 7 d at 10 ℃. [ Condusion] The research provided theoretical guiding for in situ remediation of the qroundwater contaminated bv PGBs.展开更多
A Ni-P coating was deposited on Cu substrate by electroless plating and the Al/Cu bimetal was produced by solid？liquid compound casting technology. The microstructure, mechanical properties and conductivity of Al/Cu ...A Ni-P coating was deposited on Cu substrate by electroless plating and the Al/Cu bimetal was produced by solid？liquid compound casting technology. The microstructure, mechanical properties and conductivity of Al/Cu joints with different process parameters （bonding temperature and preheating time） were investigated. The results showed that intermetallics formed at the interface and the thickness and variety increased with the increase of bonding temperature and preheating time. The Ni？P interlayer functioned as a diffusion barrier and protective film which effectively reduced the formation of intermetallics. The shear strength and conductivity of Al/Cu bimetal were reduced by increasing the thickness of intermetallics. In particular, the detrimental effect of Al2Cu phase was more obvious compared with the others. The sample preheated at 780 ℃ for 150 s exhibited the maximum shear strength and conductivity of 49.8 MPa and 5.29×10^5 S/cm, respectively.展开更多
基金funded by the National Natural Science Foundation of China(Nos.52271102,52075198 and 52205359)。
文摘In this work,a new treatment method combining ultrasonic vibration with FeCoNiCrCu high entropy alloy(HEA)coating was used to prepared Al/Mg bimetal through the lost foam compound casting.The effects of composite treatment involving ultrasonic vibration and HEA coating on interfacial microstructure and mechanical properties of Al/Mg bimetal were studied.Results demonstrate that the interface thickness of the Al/Mg bimetal with composite treatment significantly decreases to only 26.99%of the thickness observed in the untreated Al/Mg bimetal.The HEA coating hinders the diffusion between Al and Mg,resulting the significant reduction in Al/Mg intermetallic compounds in the interface.The Al/Mg bimetal interface with composite treatment is composed of Al_(3)Mg_(2)and Mg_(2)Si/AlxFeCoNiCrCu+FeCoNiCrCu/δ-Mg+Al_(12)Mg_(17)eutectic structures.The interface resulting from the composite treatment has a lower hardness than that without treatment.The acoustic cavitation and acoustic streaming effects generated by ultrasonic vibration promote the diffusion of Al elements within the HEA coating,resulting in a significant improvement in the metallurgical bonding quality on the Mg side.The fracture position shifts from the Mg side of the Al/Mg bimetal only with HEA coating to the Al side with composite treatment.The shear strength of the Al/Mg bimetal increases from 32.16 MPa without treatment to 63.44 MPa with ultrasonic vibration and HEA coating,increasing by 97.26%.
基金Projects (51274054,51375070,51271042) supported by the National Natural Science Foundation of ChinaProjects (2013M530913) supported by the China Postdoctoral Science Foundation
文摘A nickel-based coating was deposited on the pure Al substrate by immersion plating,and the Al/Cu bimetals were prepared by diffusion bonding in the temperature range of 450-550 ℃.The interce microstructure and fracture surface of Al/Cu joints were studied by scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The mechanical properties of the Al/Cu bimetals were measured by tensile shear and microhardness tests.The results show that the Ni interiayer can effectively eliminate the formation of Al-Cu intermetallic compounds.The Al/Ni interface consists of the Al3Ni and Al3Ni2 phases,while it is Ni-Cu solid solution at the Ni/Cu interce.The tensile shear strength of the joints is improved by the addition of Ni interiayer.The joint with Ni interiayer annealed at 500 ℃ exhibits a maximum value of tensile shear strength of 34.7 MPa.
文摘Compound casting is an efficient method for bonding dissimilar metals,in which a dramatic reaction can occur between the melt and solid.The centrifugal casting process,a type of compound casting,was applied to cast Al/Mg dissimilar bimetals.Magnesium melt was poured at 700 °C,with melt-to-solid volume ratios(Vm/Vs) of 1.5 and 3,into a preheated hollow aluminum cylinder.The preheating temperatures of the solid part were 320,400,and 450 °C,and the constant rotational speed was 1,600 rpm.The cast parts were kept inside the casting machine until reaching the cooling temperature of 150 °C.The result showed that an increase in preheating temperature from 320 to 450 °C led to an enhanced reaction layer thickness.In addition,an increase in the Vm/Vs from 1.5 to 3 resulted in raising the interface thickness from 1.2 to 1.8 mm.Moreover,the interface was not continuously formed when a Vm/Vs of 3 was selected.In this case,the force of contraction overcame the resultant acting force on the interface.An interface formed at the volume ratio of 1.5 was examined using scanning electron microscopy(SEM) equipped with energy-dispersive X-ray spectroscopy(EDS),and the results demonstrated the formation of Al_(3)Mg_(2),Al_(12)Mg_(17) and(δ+Al_(12)Mg_(17)) eutectic structures in the interface.
基金the supports provided by the National Natural Science Foundation of China(No.52075198)the National Key Research and Development Program of China(Nos.2020YFB2008300,2020YFB2008304)+1 种基金the State Key Lab of Advanced Metals and Materials(No.2021-ZD07)the Analytical and Testing Center,HUST。
文摘In this work,a vibration was applied in the preparation of the Mg/Al bimetal by a novel compound casting in order to improve the mechanical properties of the Mg/Al bimetal,and the effect of the vibration on the interfacial microstructure and mechanical properties of the Mg/Al bimetal was investigated.The results indicated that the vibration had a significant effect on the interfacial microstructure and mechanical properties of the Mg/Al bimetal,but it did not change the phase compositions of the interface,which was composed of layerⅠ(Al3Mg2+Mg2Si),layerⅡ(Al_(12)Mg_(17)+Mg_(2)Si)and layerⅢ(Al_(12)Mg_(17)/δ-Mg).Without vibration,the Mg_(2)Si phase with a needle-like morphology mainly aggregated in the layerⅡof the interface.After the application of the vibration,the SEM and EBSD analysis results showed that the Mg_(2)Si and Al3Mg2phases in the interface were obviously refined,and the distribution of the Mg_(2)Si became more uniform,due to the strong forced convection of the molten metal resulting from the vibration.The TEM analysis indicated that the interface between the A_(l3)Mg_(2) and Mg_(2)Si phases was non-coherent,suggesting the Mg_(2)Si particles cannot act as a heterogeneous nucleation base during the solidification process of the interface.Compared to the Mg/Al bimetal without vibration,the shear strength of the Mg/Al bimetal with vibration increased by about 50%from 31.7 MPa on average to 47.5 MPa,and the hardness of the layer I of the interface increased,and the hardness of the layerⅢdecreased.The fracture surface transformed from a flat fracture morphology without vibration to an irregular zigzag fracture morphology.
基金financial supports from the National Natural Science Foundation of China (No. 51875062)China Postdoctoral Science Foundation (No. 2021M700567)。
文摘In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer.The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis.Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg,which is conducive to the formation of solid solution,especially when the thickness of HEA is 800 nm.With the increase of casting temperature from 720 ℃ to 730 ℃,740℃,and 750 ℃,α-Al(Mg),α-Al(Mg)+Al3Mg2,Al3Mg2+Al12Mg17,and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal,respectively.When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 ℃,the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.
基金This work was funded by the National Natural Science Foundation of China(Nos.52075198,52271102 and 52205359)the China Postdoctoral Science Foundation(No.2021M691112).
文摘Al/Mg bimetal was prepared by lost foam solid-liquid compound casting,and the effects of mechanical vibration on the filling and solidification behavior,microstructure and performance of the bimetal were investigated.Results show that the mechanical vibration has a remarkable influence on the filling and solidification processes.It is found that after mechanical vibration,the filling rate increases and the filling rate at different times is more uniform than that without vibration.In addition,the mechanical vibration also increases the wettability between liquid AZ91D and A356 inlays.The mechanical vibration reduces the horizontal and vertical temperature gradient of the casting and makes the temperature distribution of the whole casting more uniform.Compared to the Al/Mg bimetal without vibration,the shear strength is improved by 39.76%after the mechanical vibration is applied,due to the decrease of the inclusions and Al_(12)Mg_(17) dendrites,and the refinement and uniform distribution of the Mg_(2)Si particles in the interface of the Al/Mg bimetal.
基金Supported by National Natural Science Fund Item,China(50879029 /E090301)Department of Science and Technology Item in Jilin Province,China(20090415)
文摘[Objective] The research aimed to study reductive dechlorination effect of PCBs in groundwater by Fe/Zn bimetal. [Method] Fe/Zn bi- metal as reduction system, PCBs degradation ratio as inspected index, degradation effect of PCBs by Fe/Zn bimetallic system when adding self- made hydroxypropyl-β-cyclodextdn （HP-β-CD） was studied. Meanwhile, we investigated the influences of loading ratio and Fe-Zn dosage on PCBs dechlorination. [ Result] PCBs was significantly solubilized by the synthesized HP-β-CD. With increase of the HP-β-CD concentration, the apparent solubility of PCBs increased linearly, forming 1：1 inclusion complex. When Fe-Zn dosage was 10 g, and mass fraction of Zn was 7%, the dechlori- nation efficiency of 321 μg/L PCBs was 47.6% after degrading for 7 d at 10 ℃. [ Condusion] The research provided theoretical guiding for in situ remediation of the qroundwater contaminated bv PGBs.
基金Project(51571080)supported by the National Natural Science Foundation of China
文摘A Ni-P coating was deposited on Cu substrate by electroless plating and the Al/Cu bimetal was produced by solid？liquid compound casting technology. The microstructure, mechanical properties and conductivity of Al/Cu joints with different process parameters （bonding temperature and preheating time） were investigated. The results showed that intermetallics formed at the interface and the thickness and variety increased with the increase of bonding temperature and preheating time. The Ni？P interlayer functioned as a diffusion barrier and protective film which effectively reduced the formation of intermetallics. The shear strength and conductivity of Al/Cu bimetal were reduced by increasing the thickness of intermetallics. In particular, the detrimental effect of Al2Cu phase was more obvious compared with the others. The sample preheated at 780 ℃ for 150 s exhibited the maximum shear strength and conductivity of 49.8 MPa and 5.29×10^5 S/cm, respectively.
基金financially supported by the Fundamental Research Funds for the Central Universities,China(No.2020CDJDPT001)the Chongqing Natural Science Foundation,China(No.cstc2021jcyj-msxm X0699)。
基金supported by the National Natural Science Foundation,China (No.52074131)the National Key R&D Project,China (No.2022YFC3900500)+2 种基金the International Technology Cooperation Program of Guangdong Academy of Sciences,China (No.2020GDASYL-20200504001)the Open Competition to Select the Best Candidate of Shangrao,China (No.2021A005)the BL13HB beamline of Shanghai Synchrotron Radiation Facility (SSRF)for providing synchrotron radiation beamtime (Nos.2020-SSRF-PT-011937,2021-SSRF-PT-017645).
