Four kinds of aluminum based moderate temperature filler metals used for vacuum brazing of 6061 aluminum alloy were prepared by rapid solidification-isothermal rolling.The effects of alloy elements content on the melt...Four kinds of aluminum based moderate temperature filler metals used for vacuum brazing of 6061 aluminum alloy were prepared by rapid solidification-isothermal rolling.The effects of alloy elements content on the melting characteristics of filler metals was studied by Differential Scanning Calorimetry(DSC).The microstructures of the filler metals and brazed joints were observed by scanning electron microscopy(SEM)and energy dispersive spectrometer(EDS).The results show that with the increase of Cu content into the filler metals,the liquid phase temperature gradually is decreased.Microstructure characterzation of the brazed joints shows the eutectic structure of(α+β)and(α+θ)decrease gradually,θ-CuAl_(2)(Ni)gradually increases and transforms from small fishbone shapes to block shapes.Peak shear strength of 83 MPa for the 6061 aluminum joint with Al-9.5Si-10Cu-2Ni-0.5Mg was achieved after brazing at 575℃for 2 min.展开更多
The Al25 Cu6. 5 SiO. 09RE （RE = La and Ce ） and Al25 Cu10. 5 Si2Ni filler metals were prepared by common metal mold casting, copper plate chilling and rapid solidification, respectively. The microstructures and prop...The Al25 Cu6. 5 SiO. 09RE （RE = La and Ce ） and Al25 Cu10. 5 Si2Ni filler metals were prepared by common metal mold casting, copper plate chilling and rapid solidification, respectively. The microstructures and properties of these filler metals were studied. The results show that the as-casting and the corresponding rapid solidification filler metals have the same phases but their microstructures are different. The microstructure of rapid solidification filler metals consists of an α-A1 solid solution, the θ （ Al2 Cu ） intermetaUic compound and an Al-Cu-Si eutectic phase. Compared with the ns-casting filler metal, the melting temperature ranges （△T） of the corresponding copper plate chilling and rapid solidification filler metals decrease and their wettabilities are improved because of the grain refinement and the improvement of composition uniformity. The wetting area of Al25Cu6. 5Si0. 09RE rapid solidification filler metal doubles that of the corresponding as-casting filler metal. It is hopeful that the properties of Al-Cu-Si filler metals will be improved by changing preparation technology.展开更多
Melting temperature, spreadability, mechanical properties and the microstructures of joints brazed with silver-base filler metals including different amounts of Ga and/or In were studied respectively in this paper, an...Melting temperature, spreadability, mechanical properties and the microstructures of joints brazed with silver-base filler metals including different amounts of Ga and/or In were studied respectively in this paper, and the results show that the melting temperature of the silver-base filler metals is decreased, spreadability of the silver-base filler metals is improved, and the microstructures of silver-base filh, r metals are refined obviously with the addition of Ga and/or In. Using copper and brass plates as base metal and brazing with flame method, the mechanical properties of the lap-joint and butt joint were also examined and analyzed respectively, and the results indicate that the fracture position of two kinds of brazed joints occurred on the base metal, except for the lap-joint of brass, which shows better mechanical properties of the joints brazed with the silver- based filler metals including Ga. For the lap-joint of brass, the tensile strength gradually increased with the increase of Ga content, while the addition of In has little effect on mechanical properties. It is also found that the best comprehensive properties of cadmium-free Ag-Cu-Zn filler metals are obtained when Ga content is about 3.0 wt. % and In content is between 1.5 wt. % and 2. 0 wt. %.展开更多
The objective of this study is to investigate the influence of adding tiny amount of mixed rare earth （ La, Ce） and Sr to Al-20Cu-SSi-2Ni filler metal, by analyzing the microstructure, wettability and mechanical pro...The objective of this study is to investigate the influence of adding tiny amount of mixed rare earth （ La, Ce） and Sr to Al-20Cu-SSi-2Ni filler metal, by analyzing the microstructure, wettability and mechanical properties of brazed joints. The results show that with the addition of mixed rare earth （La, Ce ） into Al-2OCu-SSi-2Ni alloy, the α-Al solid solution as well as CuAl2 （ Ni） intermetallic compound phase significantly reduced, while more Al-Si eutectic phase and AI-Si-Cu ternary eutectic phase were produced. And as mixed rare earth （La, Ce ） added in, the wettability of Al-2OCu-SSi-2Ni filler metal decreased, while the shear strength of the brazed joints increased. The addition of Minor Sr modificated Al-2OCu-SSi-2Ni filler metal, further reduced the CuAl2 （ Ni ） intermetallic compound phase, which was partially replaced Al-Si-Cu ternary eutectic phase. As a result, the tensile strength as well as the wettability of the filler metal was improved.展开更多
CBN/Cu-Sn-Ti(CBN: cubic boron nitride) composites are prepared by active brazing sintering at 1123 K,1173 K, 1223 K and 1273 K, respectively. The effects of brazing temperature on the wettability, interfacial characte...CBN/Cu-Sn-Ti(CBN: cubic boron nitride) composites are prepared by active brazing sintering at 1123 K,1173 K, 1223 K and 1273 K, respectively. The effects of brazing temperature on the wettability, interfacial characteristics, and elemental distribution variations are fully investigated. When the brazing temperature is below 1223 K, completely uncoated and/or partially coated CBN particles with sharp edges can still be observed, and the reaction layer, mainly composed of Ti N and Ti B2, appears to be thin and uneven.When the brazing temperature is 1223 K, all CBN particles are completely coated, suggesting that adequate wetting has taken place. Besides, as Ti diffuses thoroughly and enriches the interface, the reaction layer, filled primarily by Ti N, Ti B2 and Ti B, becomes thicker(about 1.30 μm), more uniform, stable and continuous. Further increasing the temperature to 1273 K is unnecessary or even harmful as the reaction layer thickness undergoes negligible change yet some tiny micro-cracks appear on the interface, which may likely deteriorate the grinding capability of the final brazing products.展开更多
Applications like solid oxide fuel cells and sensors increasingly demand the possibility to braze ceramics to metals with a good resistance to high temperatures and oxidative atmospheres. Commonly used silver based ac...Applications like solid oxide fuel cells and sensors increasingly demand the possibility to braze ceramics to metals with a good resistance to high temperatures and oxidative atmospheres. Commonly used silver based active filler metals cannot fulfill these requirements, if application temperatures higher than 600℃ occur. Au and Pd based active fillers are too expensive for many fields of use. As one possible solution nickel based active fillers were developed. Due to the high brazing temperatures and the low ductility of nickel based filler metals, the modification of standard nickel based filler metals were necessary to meet the requirements of above mentioned applications. To reduce thermally induced stresses wide brazing gaps and the addition of A1203 and WC particles to the filler metal were applied. In this study, the microstructure of the brazed joints and the thermo-chemical reactions between filler metal, active elements and WC particles were analyzed to understand the mechanism of the so called wide gap active brazing process. With regard to the behavior in typical application oxidation and thermal cycle tests were conducted as well as tensile tests.展开更多
文摘Four kinds of aluminum based moderate temperature filler metals used for vacuum brazing of 6061 aluminum alloy were prepared by rapid solidification-isothermal rolling.The effects of alloy elements content on the melting characteristics of filler metals was studied by Differential Scanning Calorimetry(DSC).The microstructures of the filler metals and brazed joints were observed by scanning electron microscopy(SEM)and energy dispersive spectrometer(EDS).The results show that with the increase of Cu content into the filler metals,the liquid phase temperature gradually is decreased.Microstructure characterzation of the brazed joints shows the eutectic structure of(α+β)and(α+θ)decrease gradually,θ-CuAl_(2)(Ni)gradually increases and transforms from small fishbone shapes to block shapes.Peak shear strength of 83 MPa for the 6061 aluminum joint with Al-9.5Si-10Cu-2Ni-0.5Mg was achieved after brazing at 575℃for 2 min.
文摘The Al25 Cu6. 5 SiO. 09RE （RE = La and Ce ） and Al25 Cu10. 5 Si2Ni filler metals were prepared by common metal mold casting, copper plate chilling and rapid solidification, respectively. The microstructures and properties of these filler metals were studied. The results show that the as-casting and the corresponding rapid solidification filler metals have the same phases but their microstructures are different. The microstructure of rapid solidification filler metals consists of an α-A1 solid solution, the θ （ Al2 Cu ） intermetaUic compound and an Al-Cu-Si eutectic phase. Compared with the ns-casting filler metal, the melting temperature ranges （△T） of the corresponding copper plate chilling and rapid solidification filler metals decrease and their wettabilities are improved because of the grain refinement and the improvement of composition uniformity. The wetting area of Al25Cu6. 5Si0. 09RE rapid solidification filler metal doubles that of the corresponding as-casting filler metal. It is hopeful that the properties of Al-Cu-Si filler metals will be improved by changing preparation technology.
文摘Melting temperature, spreadability, mechanical properties and the microstructures of joints brazed with silver-base filler metals including different amounts of Ga and/or In were studied respectively in this paper, and the results show that the melting temperature of the silver-base filler metals is decreased, spreadability of the silver-base filler metals is improved, and the microstructures of silver-base filh, r metals are refined obviously with the addition of Ga and/or In. Using copper and brass plates as base metal and brazing with flame method, the mechanical properties of the lap-joint and butt joint were also examined and analyzed respectively, and the results indicate that the fracture position of two kinds of brazed joints occurred on the base metal, except for the lap-joint of brass, which shows better mechanical properties of the joints brazed with the silver- based filler metals including Ga. For the lap-joint of brass, the tensile strength gradually increased with the increase of Ga content, while the addition of In has little effect on mechanical properties. It is also found that the best comprehensive properties of cadmium-free Ag-Cu-Zn filler metals are obtained when Ga content is about 3.0 wt. % and In content is between 1.5 wt. % and 2. 0 wt. %.
文摘The objective of this study is to investigate the influence of adding tiny amount of mixed rare earth （ La, Ce） and Sr to Al-20Cu-SSi-2Ni filler metal, by analyzing the microstructure, wettability and mechanical properties of brazed joints. The results show that with the addition of mixed rare earth （La, Ce ） into Al-2OCu-SSi-2Ni alloy, the α-Al solid solution as well as CuAl2 （ Ni） intermetallic compound phase significantly reduced, while more Al-Si eutectic phase and AI-Si-Cu ternary eutectic phase were produced. And as mixed rare earth （La, Ce ） added in, the wettability of Al-2OCu-SSi-2Ni filler metal decreased, while the shear strength of the brazed joints increased. The addition of Minor Sr modificated Al-2OCu-SSi-2Ni filler metal, further reduced the CuAl2 （ Ni ） intermetallic compound phase, which was partially replaced Al-Si-Cu ternary eutectic phase. As a result, the tensile strength as well as the wettability of the filler metal was improved.
基金supported financially by the National Natural Science Foundation of China (Nos. 51622401, 51628402, 51861130361, 51861145312 and 51850410522)the Newton Advanced Fellowship by Royal Society (No. RP12G0414)+3 种基金the Research Fund for Central Universities (No. N172502004)the National Key Research and Development Program of China (No.2016YFB0300602)the Global Talents Recruitment Program endowed by the Chinese GovernmentState Key Laboratory of Solidification Processing, Northwestern Polytechnical University (No. SKLSP201805)
文摘CBN/Cu-Sn-Ti(CBN: cubic boron nitride) composites are prepared by active brazing sintering at 1123 K,1173 K, 1223 K and 1273 K, respectively. The effects of brazing temperature on the wettability, interfacial characteristics, and elemental distribution variations are fully investigated. When the brazing temperature is below 1223 K, completely uncoated and/or partially coated CBN particles with sharp edges can still be observed, and the reaction layer, mainly composed of Ti N and Ti B2, appears to be thin and uneven.When the brazing temperature is 1223 K, all CBN particles are completely coated, suggesting that adequate wetting has taken place. Besides, as Ti diffuses thoroughly and enriches the interface, the reaction layer, filled primarily by Ti N, Ti B2 and Ti B, becomes thicker(about 1.30 μm), more uniform, stable and continuous. Further increasing the temperature to 1273 K is unnecessary or even harmful as the reaction layer thickness undergoes negligible change yet some tiny micro-cracks appear on the interface, which may likely deteriorate the grinding capability of the final brazing products.
文摘Applications like solid oxide fuel cells and sensors increasingly demand the possibility to braze ceramics to metals with a good resistance to high temperatures and oxidative atmospheres. Commonly used silver based active filler metals cannot fulfill these requirements, if application temperatures higher than 600℃ occur. Au and Pd based active fillers are too expensive for many fields of use. As one possible solution nickel based active fillers were developed. Due to the high brazing temperatures and the low ductility of nickel based filler metals, the modification of standard nickel based filler metals were necessary to meet the requirements of above mentioned applications. To reduce thermally induced stresses wide brazing gaps and the addition of A1203 and WC particles to the filler metal were applied. In this study, the microstructure of the brazed joints and the thermo-chemical reactions between filler metal, active elements and WC particles were analyzed to understand the mechanism of the so called wide gap active brazing process. With regard to the behavior in typical application oxidation and thermal cycle tests were conducted as well as tensile tests.
