Electron beam welding was carried out between aluminum alloy and steel with Ag interlayer. Seam morphology, structure and mechanical properties of the joints were investigated with different action positions of the el...Electron beam welding was carried out between aluminum alloy and steel with Ag interlayer. Seam morphology, structure and mechanical properties of the joints were investigated with different action positions of the electron beam spot. The results show that with the increment of the beam offset to the silver side from the interface between silver and steel, the seam morphology was improved, and the porosity in the Ag interlayer vanished. A transition layer mainly composed of Ag2Al and Al eutectic was formed at the interface between silver and aluminum, and became thin and spiccato as the beam offset increased. When the beam offset was too large, two IMC layers composed of FeAl and FeAl3 respectively were formed at the interface between steel and Ag interlayer. The optimal beam offset was 0.2 mm, and the maximum tensile strength of the joint was 193 MPa, 88.9% that of the aluminum alloy, and the fracture occurred at the interface between steel and Ag interlayer.展开更多
Lightweight ZEK100-0 Mg alloy and A16022-T43 Al alloy with an Ag interlayer were joined via ultrasonic spot welding(USW),focusing on the microstructural change and tensile lap shear strength of the welded joints in re...Lightweight ZEK100-0 Mg alloy and A16022-T43 Al alloy with an Ag interlayer were joined via ultrasonic spot welding(USW),focusing on the microstructural change and tensile lap shear strength of the welded joints in relation to welding energy.Mg/Al interface was superseded by Mg/Ag and Al/Ag interfaces,and unfavorable Mg门A-intermetallic compound was eliminated.Ag foil was observed to be intact in the nugget center,while it was broken or dissolved at the nugget edge at high welding energy levels.The diffusion layer at the Mg/Ag interface consisted of two distinctive sub-layers:Mg3Ag intermetallic compound adjoining Ag foil,and Mg3Ag-l-Mg eutectic structure adjacent to Mg.Only a thin diffusion layer consisting mainly of Ag3Al occurred al lhe Al/Ag interface.The tensile lap shear strength first increased,reached its peak value,and then decreased with increasing welding energy.The shear strength achieved in the present study was〜31%higher than that of the joint without interlayer.Interfacial failure occurred at all energy levels,with Ag foil particles or fragments being stuck on both Mg and Al sides due to its intense interaction with Mg and Al via accelerated diffusion during USW.The results obtained pave the way for the challenging dissimilar welding between Mg and Al alloys.展开更多
One of the critical challenges for the protonic ceramic fuel cell stack is sealing electrolytes and interconnects.However,the traditional AgeCuO sealant will aggravate the oxidation along the interconnect surface and ...One of the critical challenges for the protonic ceramic fuel cell stack is sealing electrolytes and interconnects.However,the traditional AgeCuO sealant will aggravate the oxidation along the interconnect surface and result in brittle compound layers at the BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ)(BZCYYb)electrolyte interface.The present work demonstrates that a silver particle interlayer with high dislocation density can be adopted to join BZCYYb electrolyte to the interconnect(AISI 441 stainless)in air instead of traditional AgeCuO sealant.Elevating temperatures result in a sufficient bonding at the Ag/BZCYYb interface,and a defect-free joint is obtained at 950℃.Atomic bonding at Ag/BZCYYb interface is confirmed by TEM.Also,a dense and thin oxide layer(2-3 μm)is formed along the AISI 441 interface.Ag particles in the interlayer provide the main driving force for the sintering joining.The massive dislocations promote the recovery and recrystallization of the Ag interlayer,as well as the interdiffusion of BZCYYb/Ag.After aging in the wet oxidizing atmosphere at 600℃ for 300 h,joints remain intact and dense,indicating superior oxidation resistance and aging performance.Besides,the joint shear strength(25.3 MPa)is 59%higher than that of the joint brazed by traditional AgeCuO.展开更多
基金Project (2010CB731704) supported by the National Basic Research Program of ChinaProject (51075089) supported by the National Natural Science Foundation of china
文摘Electron beam welding was carried out between aluminum alloy and steel with Ag interlayer. Seam morphology, structure and mechanical properties of the joints were investigated with different action positions of the electron beam spot. The results show that with the increment of the beam offset to the silver side from the interface between silver and steel, the seam morphology was improved, and the porosity in the Ag interlayer vanished. A transition layer mainly composed of Ag2Al and Al eutectic was formed at the interface between silver and aluminum, and became thin and spiccato as the beam offset increased. When the beam offset was too large, two IMC layers composed of FeAl and FeAl3 respectively were formed at the interface between steel and Ag interlayer. The optimal beam offset was 0.2 mm, and the maximum tensile strength of the joint was 193 MPa, 88.9% that of the aluminum alloy, and the fracture occurred at the interface between steel and Ag interlayer.
基金The authors would like to thank the National Natural Science Foundation of China(Grant No.51971183)Natural Sciences and Engineering Research Council of Canada(NSERC)+1 种基金Fundamental Research Funds for the Central Universities(XDJK2018B108,SWU119065)Venture and Innovation Support Program for Chongqing Overseas Returnees(CX2018082)in the form of international research collaboration.
文摘Lightweight ZEK100-0 Mg alloy and A16022-T43 Al alloy with an Ag interlayer were joined via ultrasonic spot welding(USW),focusing on the microstructural change and tensile lap shear strength of the welded joints in relation to welding energy.Mg/Al interface was superseded by Mg/Ag and Al/Ag interfaces,and unfavorable Mg门A-intermetallic compound was eliminated.Ag foil was observed to be intact in the nugget center,while it was broken or dissolved at the nugget edge at high welding energy levels.The diffusion layer at the Mg/Ag interface consisted of two distinctive sub-layers:Mg3Ag intermetallic compound adjoining Ag foil,and Mg3Ag-l-Mg eutectic structure adjacent to Mg.Only a thin diffusion layer consisting mainly of Ag3Al occurred al lhe Al/Ag interface.The tensile lap shear strength first increased,reached its peak value,and then decreased with increasing welding energy.The shear strength achieved in the present study was〜31%higher than that of the joint without interlayer.Interfacial failure occurred at all energy levels,with Ag foil particles or fragments being stuck on both Mg and Al sides due to its intense interaction with Mg and Al via accelerated diffusion during USW.The results obtained pave the way for the challenging dissimilar welding between Mg and Al alloys.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China under Grant[U1737205 and 51805114]the China Postdoctoral Science Foundation 2019TQ0075.
文摘One of the critical challenges for the protonic ceramic fuel cell stack is sealing electrolytes and interconnects.However,the traditional AgeCuO sealant will aggravate the oxidation along the interconnect surface and result in brittle compound layers at the BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ)(BZCYYb)electrolyte interface.The present work demonstrates that a silver particle interlayer with high dislocation density can be adopted to join BZCYYb electrolyte to the interconnect(AISI 441 stainless)in air instead of traditional AgeCuO sealant.Elevating temperatures result in a sufficient bonding at the Ag/BZCYYb interface,and a defect-free joint is obtained at 950℃.Atomic bonding at Ag/BZCYYb interface is confirmed by TEM.Also,a dense and thin oxide layer(2-3 μm)is formed along the AISI 441 interface.Ag particles in the interlayer provide the main driving force for the sintering joining.The massive dislocations promote the recovery and recrystallization of the Ag interlayer,as well as the interdiffusion of BZCYYb/Ag.After aging in the wet oxidizing atmosphere at 600℃ for 300 h,joints remain intact and dense,indicating superior oxidation resistance and aging performance.Besides,the joint shear strength(25.3 MPa)is 59%higher than that of the joint brazed by traditional AgeCuO.
