Recently,the presentation of the metal-ceramic composite structure design provides an alternative idea for the improvement of components service performance,while conventional methods for joining metals and ceramics h...Recently,the presentation of the metal-ceramic composite structure design provides an alternative idea for the improvement of components service performance,while conventional methods for joining metals and ceramics have to involve a high heat input.However,due to the low melting point of magnesium alloys,the magnesium alloys-ceramics joining system necessitates a low joining temperature.Ultrasonic vibrations can induce numerous defects in the solid matrix,which can effectively promote atomic diffusion and metallurgical bonding between solid-phase interfaces at low temperatures.Thus,ultrasonic-assisted bonding is a highly promising method for achieving rapid and reliable joining between metals and ceramics without the use of interlayers.In this study,the direct bonding of AZ31B alloy with ZrO_(2) ceramic was successfully achieved at 200℃.A polycrystal spinel MgAl_(2)O_(4) with an average thickness of 55 nm was identified at the AZ31B/ZrO_(2) interface.The average shear strength of joints reached 30.47 MPa.Furthermore,the dynamic recrystallization of AZ31B and the oxygendepletion behavior of ZrO_(2) during the bonding process were characterized to illustrate the contribution of ultrasonic vibration to joint bonding.Consequently,the solid interfacial sono-oxidation reaction is proposed to discuss the bonding mechanism of the joint in detail.展开更多
We demonstrate a process to achieve selective surface metallization of ZrO_(2)ceramics using ultrasound technology in atmospheric environments at 350℃,which bestows good weldability of ZrO_(2)to achieve rapid and rel...We demonstrate a process to achieve selective surface metallization of ZrO_(2)ceramics using ultrasound technology in atmospheric environments at 350℃,which bestows good weldability of ZrO_(2)to achieve rapid and reliable connections with other metals as well as ceramic materials.The challenge is that brazing or diffusion welding processes to accomplish metallurgical connections for ZrO_(2) typically require holding at elevated temperatures for minutes to hours,while the selective ultrasonic metallization process requires only a few seconds of processing without the application of covering films or solder resists.In this study,the selected Sn-2Ti alloy could effectively wet and spread on ZrO_(2)substrate under ultrasonication,and continuous interphase layers were rapidly formed in situ between ZrO_(2)and Sn-2Ti.The bonding strength for the ZrO_(2)/Sn-2Ti interface was well established with the highest shear strength of 37.1 MPa,and the fracture location occurred at the filler metal.The interfacial reaction layer thickened remarkably with the prolongation of sonication,accompanied by the partial crystallization of amorphous TiO and the formation of irregularly striped Ti_(11.31)Sn_(3)O_(10)nanocrystals.展开更多
In this study,a novel eutectic-reaction brazing of Al_(0.3)CoCrFeNi high-entropy alloys(HEAs)^(1)was investigated with a design of laminated Ni/Nb/Ni interlayers.The typical Al_(0.3)CoCrFeNi brazing seam consisted of ...In this study,a novel eutectic-reaction brazing of Al_(0.3)CoCrFeNi high-entropy alloys(HEAs)^(1)was investigated with a design of laminated Ni/Nb/Ni interlayers.The typical Al_(0.3)CoCrFeNi brazing seam consisted of proeutecticγ,the lamellar eutectic structure composed of face-centered cubic(FCC)phase(eutecticγ)and C14 Laves,as well as a few amounts of Nb based solid solution.A high density of nanoscale ordered L1_(2)(γ)phase was precipitated withinγphase matrix.With the brazing temperature raised from 1200 to 1320℃,the dissolution volume of Al_(0.3)CoCrFeNi alloy into Ni-Nb liquid was increased.The microstructure of the brazing seam changed from hypereutectic(blocky Laves+γphase)to eutectic(Laves+eutecticγ)to hypoeutectic structures(proeutecticγ+Laves/γeutectic structure).The shear strength of joints was increased gradually due to the formation of eutectic lamellae and the cellular growth of proeutecticγphase.The maximum shear strength of the joint brazed at 1320℃for 10 min was up to 592 MPa,reaching 95%of the base metal.The joint mainly ruptured in the soft proeutecticγphase in a ductile fracture mode.展开更多
基金supported by the Shandong Provincial Natural Science Foundation(ZR2023ME111).
文摘Recently,the presentation of the metal-ceramic composite structure design provides an alternative idea for the improvement of components service performance,while conventional methods for joining metals and ceramics have to involve a high heat input.However,due to the low melting point of magnesium alloys,the magnesium alloys-ceramics joining system necessitates a low joining temperature.Ultrasonic vibrations can induce numerous defects in the solid matrix,which can effectively promote atomic diffusion and metallurgical bonding between solid-phase interfaces at low temperatures.Thus,ultrasonic-assisted bonding is a highly promising method for achieving rapid and reliable joining between metals and ceramics without the use of interlayers.In this study,the direct bonding of AZ31B alloy with ZrO_(2) ceramic was successfully achieved at 200℃.A polycrystal spinel MgAl_(2)O_(4) with an average thickness of 55 nm was identified at the AZ31B/ZrO_(2) interface.The average shear strength of joints reached 30.47 MPa.Furthermore,the dynamic recrystallization of AZ31B and the oxygendepletion behavior of ZrO_(2) during the bonding process were characterized to illustrate the contribution of ultrasonic vibration to joint bonding.Consequently,the solid interfacial sono-oxidation reaction is proposed to discuss the bonding mechanism of the joint in detail.
基金financially supported by the National Natural Science Foundation of China(No.51805111).
文摘We demonstrate a process to achieve selective surface metallization of ZrO_(2)ceramics using ultrasound technology in atmospheric environments at 350℃,which bestows good weldability of ZrO_(2)to achieve rapid and reliable connections with other metals as well as ceramic materials.The challenge is that brazing or diffusion welding processes to accomplish metallurgical connections for ZrO_(2) typically require holding at elevated temperatures for minutes to hours,while the selective ultrasonic metallization process requires only a few seconds of processing without the application of covering films or solder resists.In this study,the selected Sn-2Ti alloy could effectively wet and spread on ZrO_(2)substrate under ultrasonication,and continuous interphase layers were rapidly formed in situ between ZrO_(2)and Sn-2Ti.The bonding strength for the ZrO_(2)/Sn-2Ti interface was well established with the highest shear strength of 37.1 MPa,and the fracture location occurred at the filler metal.The interfacial reaction layer thickened remarkably with the prolongation of sonication,accompanied by the partial crystallization of amorphous TiO and the formation of irregularly striped Ti_(11.31)Sn_(3)O_(10)nanocrystals.
基金the National Natural Science Foundation of China(Nos.52175307,51775138 and U1737205)the Taishan Scholars Foundation of Shandong Province(No.tsqn201812128)。
文摘In this study,a novel eutectic-reaction brazing of Al_(0.3)CoCrFeNi high-entropy alloys(HEAs)^(1)was investigated with a design of laminated Ni/Nb/Ni interlayers.The typical Al_(0.3)CoCrFeNi brazing seam consisted of proeutecticγ,the lamellar eutectic structure composed of face-centered cubic(FCC)phase(eutecticγ)and C14 Laves,as well as a few amounts of Nb based solid solution.A high density of nanoscale ordered L1_(2)(γ)phase was precipitated withinγphase matrix.With the brazing temperature raised from 1200 to 1320℃,the dissolution volume of Al_(0.3)CoCrFeNi alloy into Ni-Nb liquid was increased.The microstructure of the brazing seam changed from hypereutectic(blocky Laves+γphase)to eutectic(Laves+eutecticγ)to hypoeutectic structures(proeutecticγ+Laves/γeutectic structure).The shear strength of joints was increased gradually due to the formation of eutectic lamellae and the cellular growth of proeutecticγphase.The maximum shear strength of the joint brazed at 1320℃for 10 min was up to 592 MPa,reaching 95%of the base metal.The joint mainly ruptured in the soft proeutecticγphase in a ductile fracture mode.
