Electrochemical behavior of LiB compound in LiPF6-DMC/EMC/EC was studied. And morphology of the compound was investigated by SEM. The results show that there are three discharge potential plateaus for the LiB compound...Electrochemical behavior of LiB compound in LiPF6-DMC/EMC/EC was studied. And morphology of the compound was investigated by SEM. The results show that there are three discharge potential plateaus for the LiB compound, corresponding to 0.46, 0.69 and 0.8 V (vs Li+/Li) respectively, its total discharge specific capacity is up to 660 mA·h/g, only first two potential plateau can be charged, its specific capacity is 274 mA·h/g. After discharging, the morphology of the Li compound is still fibrous shape.展开更多
The galvanized steels were joined using a TIG arc brazing process with CuSi3 as the filler metal.The arcing time ranged from 1 s to 5 s with arcing current of 70 A in flowing argon.The possible reaction products at th...The galvanized steels were joined using a TIG arc brazing process with CuSi3 as the filler metal.The arcing time ranged from 1 s to 5 s with arcing current of 70 A in flowing argon.The possible reaction products at the interface were confirmed using thermodynamics,SEM,and EDS methods.The results show that a fragmention behavior in some whisker-like intermetallic compounds happens,and that there are two layers of Fe2Si and Fe5Si3 formed at the interface of the galvanized steel and copper filler.From this,the schematic cycle of the interface growth behavior of Fe/Si compounds and the fragmentation behavior of whisker-like intermetallic compounds are developed.展开更多
The influence of lanthanum on the microstructure, deformed behavior, microcrack susceptibility of intermetallic compound Al 66 Mn 9Ti 25 was investigated. Adding lanthanum into intermetallic compound Al 6...The influence of lanthanum on the microstructure, deformed behavior, microcrack susceptibility of intermetallic compound Al 66 Mn 9Ti 25 was investigated. Adding lanthanum into intermetallic compound Al 66 Mn 9Ti 25 , the lattice parameters are not changed and the Ll 2 structure is maintained. At the same time, the dendritical grain and fine second phase are obtained, which inhibits the microcrack initiation and intergranular failure. On the other hand, the movability of dislocation is enhanced and the compressive ductility is improved. The mechanism about the role of lanthanum in intermetallic compound Al 66 Mn 9Ti 25 was discussed.展开更多
With the Uddeholm self restricted method, the effect of compound layer of plasma nitriding on thermal fatigue behavior of 4Cr5MoSiV1 steel was studied by the way of adding Ar during plasma nitriding to remove the com...With the Uddeholm self restricted method, the effect of compound layer of plasma nitriding on thermal fatigue behavior of 4Cr5MoSiV1 steel was studied by the way of adding Ar during plasma nitriding to remove the compound layer. The results show that the compound layer of plasma nitriding can delay the nucleation of heat cracks and hold back the propagation of heat cracks from surface to substrate because of its high hardness and strength. On the other land, the heat checking expands faster with the compound layer on the surface than that without it. After 3000 cycles of thermal fatigue test, both heat cracks with the compound layer are wider than the another without compound layer and the number of heat cracks of the former is more from the view of cross section.展开更多
A method based on electronic structure calculation is proposed to predict the substitution behavior of elements in ordered intermetallics. The electronic structure of 20 alloying elements in TiAl is calculated using ...A method based on electronic structure calculation is proposed to predict the substitution behavior of elements in ordered intermetallics. The electronic structure of 20 alloying elements in TiAl is calculated using the DV-Xα cluster method The bond orders between alloying elements and surrounding atoms, Bo_Ti,Bo_Al, are used as parameters. Two lines on the Bo_Ti-Bo_Al diagram separate the elements into three groups. The elements located outside of the two lines substitute either Ti or Al atom regardless of the composition of TiAl. The substitution behavior of elements between the two lines will be affected by the Ti/Al ratio and the amount of alloying elements added Substituting sequence in multi-element alloy is discussed The prediction based on this method agrees well with the experimental results.展开更多
The microstructure, interface thickness, element distribution and interfacial mechanical behavior of Ti-6Al-4V/Al couples prepared by an insert moulding method were investigated in depth in this paper. Moreover, Ti/Al...The microstructure, interface thickness, element distribution and interfacial mechanical behavior of Ti-6Al-4V/Al couples prepared by an insert moulding method were investigated in depth in this paper. Moreover, Ti/Al bonding was also given as a comparison for understanding the interface bonding mechanism. It is shown that there is much thinner compact sub-layer for the interface of the Ti-6Al-4V/Al joint, whose morphology is obviously different from that of the Ti/Al joint. The Ti-6Al-4V/Al interface has been proven to contain a slight content of vanadium. Moreover, both the shear strength and the interface reaction rate of Ti-6Al-4V/Al compound materials are lower than those of the Ti/Al ones.展开更多
The diffusion behavior and reactions between AI and Ca in Mg alloys by diffusion couple method were investigated. Results demonstrate that Al2Ca is the only phase existing in the diffusion reaction layers. The volume ...The diffusion behavior and reactions between AI and Ca in Mg alloys by diffusion couple method were investigated. Results demonstrate that Al2Ca is the only phase existing in the diffusion reaction layers. The volume fraction of Al2Ca in diffusion reaction layers increases linearly with temperature. The standard enthalpy of formation for intermetallic compounds was rationalized on the basis of the Miedema model. Al-Ca intermetallic compounds were preferable to form in the Mg-Al-Ca ternary system under the same conditions. Over the range of 350-400℃, the structure of Al2Ca is more stable than that of Al4Ca, Al14Ca13and Al3Ca8, The growth constants of the layer I, layer II and entire diffusion reaction layers were determined. The activation energies for the growth of the layer I, layer II and entire diffusion reaction layers were （80.74 ± 3.01 ） kJ/mol, （93.45 ±2.12） kJ/mol and （83.52 ±1.50） kJ/mot, respectively. In layer I and II, AI has higher integrated interdiffusion coefficients D^i^Int,layer layer than Ca. The average effective interdiffusion coefficients D^Al^eff values are higher than D^Ca^eff in the layer I and II.展开更多
The magnetocaloric effect（MCE） in EuCu1.75P2 compound is studied by the magnetization and heat capacity measurements.Magnetization and modified Arrott plots indicate that the compound undergoes a second-order phase ...The magnetocaloric effect（MCE） in EuCu1.75P2 compound is studied by the magnetization and heat capacity measurements.Magnetization and modified Arrott plots indicate that the compound undergoes a second-order phase transition at TC ～ 51 K.A large reversible MCE is observed around TC.The values of maximum magnetic entropy change（-△SxMma） reach 5.6 J·kg^-1·K-1 and 13.3 J·kg^-1·K-1 for the field change of 2 T and 7 T,respectively,with no obvious hysteresis loss in the vicinity of Curie temperature.The corresponding maximum adiabatic temperature changes（△Tadmax） are evaluated to be 2.1 K and 5.0 K.The magnetic transition and the origin of large MCE in EuCu1.75P2 are also discussed.展开更多
We present the temperature-dependent susceptibility and specific heat measurement of spinel ZnV204. The structural transition with orbital ordering and the antiferromagnetic transition with spin ordering were observed...We present the temperature-dependent susceptibility and specific heat measurement of spinel ZnV204. The structural transition with orbital ordering and the antiferromagnetic transition with spin ordering were observed at 50 K and 37 K, respectively. By analysis of the hysteresis behavior between the specific heat curves obtained in warming and cooling processes, the structural transition was confirmed to be the first-order transition, while the antiferromagnetic transition was found to be of the second-order type. At the structural transition, the latent heat and entropy change were calculated from the excess specific heat, and the derivative of pressure with respect to temperature was obtained using the Clausius--Clapayron equation. At the magnetic transition, the width of the critical fluctuation region was obtained to be about 0.5 K by comparing with Gaussian fluctuations. In the critical region, the critical behavior was analyzed by using renormalization-group theory. The critical amplitude ratio A＋/A- = 1.46, which deviates from the 3D Heisenburg model; while the critical exponent a is -0.011, which is close to the 3D XY model. We proposed that these abnormal critical behaviors can be attributed to strong spin-orbital coupling accompanied with the antiferromagnetic transition. Moreover, in the low temperature range （2-5 K）, the Fermi energy, the density of states near the Fermi surface, and the low limit of Debye temperature were estimated to be 2.42 eV, 2.48 eV-1, and 240 K, respectively.展开更多
The effects of different Bi contents on the properties of Sn solders were studied. The interfacial reaction and growth behavior of intermetallic compounds（IMCs） layer（η-Cu6 Sn5 + e-Cu3 Sn） for various soldering t...The effects of different Bi contents on the properties of Sn solders were studied. The interfacial reaction and growth behavior of intermetallic compounds（IMCs） layer（η-Cu6 Sn5 + e-Cu3 Sn） for various soldering time and the influence of Bi addition on the thermal behavior of Sn-x Bi solder alloys were investigated. The Cu6 Sn5 IMC could be observed as long as the molten solder contacted with the Cu substrate. However, with the longer welding time such as 60 and 300 s, the Cu3 Sn IMC was formed at the interface between Cu6 Sn5 and Cu substrate. With the increase of soldering time, the thickness of total IMCs increased, meanwhile, the grain size of Cu6 Sn5 also increased. An appropriate amount of Bi element was beneficial for the growth of total IMCs,but excessive Bi（≥ 5 wt%） inhibited the growth of Cu6 Sn5 and Cu3 Sn IMC in Sn-x Bi/Cu microelectronic interconnects. Furthermore, with the Bi contents increasing（Sn-10 Bi solder in this present investigation）, some Bi particles accumulated at the interface between Cu6 Sn5 layer and the solder.展开更多
基金Project(50172062) supported by the National Natural Science Foundation of China
文摘Electrochemical behavior of LiB compound in LiPF6-DMC/EMC/EC was studied. And morphology of the compound was investigated by SEM. The results show that there are three discharge potential plateaus for the LiB compound, corresponding to 0.46, 0.69 and 0.8 V (vs Li+/Li) respectively, its total discharge specific capacity is up to 660 mA·h/g, only first two potential plateau can be charged, its specific capacity is 274 mA·h/g. After discharging, the morphology of the Li compound is still fibrous shape.
基金Project(50475051) supported by the National Natural Science Foundation of China
文摘The galvanized steels were joined using a TIG arc brazing process with CuSi3 as the filler metal.The arcing time ranged from 1 s to 5 s with arcing current of 70 A in flowing argon.The possible reaction products at the interface were confirmed using thermodynamics,SEM,and EDS methods.The results show that a fragmention behavior in some whisker-like intermetallic compounds happens,and that there are two layers of Fe2Si and Fe5Si3 formed at the interface of the galvanized steel and copper filler.From this,the schematic cycle of the interface growth behavior of Fe/Si compounds and the fragmentation behavior of whisker-like intermetallic compounds are developed.
文摘The influence of lanthanum on the microstructure, deformed behavior, microcrack susceptibility of intermetallic compound Al 66 Mn 9Ti 25 was investigated. Adding lanthanum into intermetallic compound Al 66 Mn 9Ti 25 , the lattice parameters are not changed and the Ll 2 structure is maintained. At the same time, the dendritical grain and fine second phase are obtained, which inhibits the microcrack initiation and intergranular failure. On the other hand, the movability of dislocation is enhanced and the compressive ductility is improved. The mechanism about the role of lanthanum in intermetallic compound Al 66 Mn 9Ti 25 was discussed.
文摘With the Uddeholm self restricted method, the effect of compound layer of plasma nitriding on thermal fatigue behavior of 4Cr5MoSiV1 steel was studied by the way of adding Ar during plasma nitriding to remove the compound layer. The results show that the compound layer of plasma nitriding can delay the nucleation of heat cracks and hold back the propagation of heat cracks from surface to substrate because of its high hardness and strength. On the other land, the heat checking expands faster with the compound layer on the surface than that without it. After 3000 cycles of thermal fatigue test, both heat cracks with the compound layer are wider than the another without compound layer and the number of heat cracks of the former is more from the view of cross section.
文摘A method based on electronic structure calculation is proposed to predict the substitution behavior of elements in ordered intermetallics. The electronic structure of 20 alloying elements in TiAl is calculated using the DV-Xα cluster method The bond orders between alloying elements and surrounding atoms, Bo_Ti,Bo_Al, are used as parameters. Two lines on the Bo_Ti-Bo_Al diagram separate the elements into three groups. The elements located outside of the two lines substitute either Ti or Al atom regardless of the composition of TiAl. The substitution behavior of elements between the two lines will be affected by the Ti/Al ratio and the amount of alloying elements added Substituting sequence in multi-element alloy is discussed The prediction based on this method agrees well with the experimental results.
基金supported by The Fundamental Research Funds for the Central Universities(No.FRF-TD-12-001)Constructed Project for the Key Laboratory of Beijing(No.FRF-SD-B-378 005B)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120006110019)the Opening Research Fund of State Key Laboratory for Advanced Metals and Materials(No.2012Z-13)
文摘The microstructure, interface thickness, element distribution and interfacial mechanical behavior of Ti-6Al-4V/Al couples prepared by an insert moulding method were investigated in depth in this paper. Moreover, Ti/Al bonding was also given as a comparison for understanding the interface bonding mechanism. It is shown that there is much thinner compact sub-layer for the interface of the Ti-6Al-4V/Al joint, whose morphology is obviously different from that of the Ti/Al joint. The Ti-6Al-4V/Al interface has been proven to contain a slight content of vanadium. Moreover, both the shear strength and the interface reaction rate of Ti-6Al-4V/Al compound materials are lower than those of the Ti/Al ones.
基金financial supports from the Scientific and Technological Research Program of Chongqing Municipal Education Commission (KJ1712301, KJ1601302)Chongqing Science and Technology Commission (cstc2017jcyj AX0394, cstc2017jcyj A1019)+1 种基金the Research Foundation of Yangtze Normal University (2016RYQD15, 2016XJQN32)the National Natural Science Foundation of China (51701033)
文摘The diffusion behavior and reactions between AI and Ca in Mg alloys by diffusion couple method were investigated. Results demonstrate that Al2Ca is the only phase existing in the diffusion reaction layers. The volume fraction of Al2Ca in diffusion reaction layers increases linearly with temperature. The standard enthalpy of formation for intermetallic compounds was rationalized on the basis of the Miedema model. Al-Ca intermetallic compounds were preferable to form in the Mg-Al-Ca ternary system under the same conditions. Over the range of 350-400℃, the structure of Al2Ca is more stable than that of Al4Ca, Al14Ca13and Al3Ca8, The growth constants of the layer I, layer II and entire diffusion reaction layers were determined. The activation energies for the growth of the layer I, layer II and entire diffusion reaction layers were （80.74 ± 3.01 ） kJ/mol, （93.45 ±2.12） kJ/mol and （83.52 ±1.50） kJ/mot, respectively. In layer I and II, AI has higher integrated interdiffusion coefficients D^i^Int,layer layer than Ca. The average effective interdiffusion coefficients D^Al^eff values are higher than D^Ca^eff in the layer I and II.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11004044)the Natural Science Foundation of Zhejiang Province,China(Grant No. Y4110581)
文摘The magnetocaloric effect（MCE） in EuCu1.75P2 compound is studied by the magnetization and heat capacity measurements.Magnetization and modified Arrott plots indicate that the compound undergoes a second-order phase transition at TC ～ 51 K.A large reversible MCE is observed around TC.The values of maximum magnetic entropy change（-△SxMma） reach 5.6 J·kg^-1·K-1 and 13.3 J·kg^-1·K-1 for the field change of 2 T and 7 T,respectively,with no obvious hysteresis loss in the vicinity of Curie temperature.The corresponding maximum adiabatic temperature changes（△Tadmax） are evaluated to be 2.1 K and 5.0 K.The magnetic transition and the origin of large MCE in EuCu1.75P2 are also discussed.
基金supported by the National Basic Research Program of China(Grant No.2012CB821404)the National Natural Science Foundation of China(Grant Nos.51172166 and 61106005)+1 种基金the National Science Fund for Talent Training in Basic Science,China(Grant No.J1210061)the Doctoral Fund of Ministry of Education of China(Grant No.20110141110007)
文摘We present the temperature-dependent susceptibility and specific heat measurement of spinel ZnV204. The structural transition with orbital ordering and the antiferromagnetic transition with spin ordering were observed at 50 K and 37 K, respectively. By analysis of the hysteresis behavior between the specific heat curves obtained in warming and cooling processes, the structural transition was confirmed to be the first-order transition, while the antiferromagnetic transition was found to be of the second-order type. At the structural transition, the latent heat and entropy change were calculated from the excess specific heat, and the derivative of pressure with respect to temperature was obtained using the Clausius--Clapayron equation. At the magnetic transition, the width of the critical fluctuation region was obtained to be about 0.5 K by comparing with Gaussian fluctuations. In the critical region, the critical behavior was analyzed by using renormalization-group theory. The critical amplitude ratio A＋/A- = 1.46, which deviates from the 3D Heisenburg model; while the critical exponent a is -0.011, which is close to the 3D XY model. We proposed that these abnormal critical behaviors can be attributed to strong spin-orbital coupling accompanied with the antiferromagnetic transition. Moreover, in the low temperature range （2-5 K）, the Fermi energy, the density of states near the Fermi surface, and the low limit of Debye temperature were estimated to be 2.42 eV, 2.48 eV-1, and 240 K, respectively.
基金Funded by the National Natural Science Foundation of China(No.51465039)Natural Science Foundation of Jiangxi Province(No.20151BAB206041,20161BAB206122)Fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP201508)
文摘The effects of different Bi contents on the properties of Sn solders were studied. The interfacial reaction and growth behavior of intermetallic compounds（IMCs） layer（η-Cu6 Sn5 + e-Cu3 Sn） for various soldering time and the influence of Bi addition on the thermal behavior of Sn-x Bi solder alloys were investigated. The Cu6 Sn5 IMC could be observed as long as the molten solder contacted with the Cu substrate. However, with the longer welding time such as 60 and 300 s, the Cu3 Sn IMC was formed at the interface between Cu6 Sn5 and Cu substrate. With the increase of soldering time, the thickness of total IMCs increased, meanwhile, the grain size of Cu6 Sn5 also increased. An appropriate amount of Bi element was beneficial for the growth of total IMCs,but excessive Bi（≥ 5 wt%） inhibited the growth of Cu6 Sn5 and Cu3 Sn IMC in Sn-x Bi/Cu microelectronic interconnects. Furthermore, with the Bi contents increasing（Sn-10 Bi solder in this present investigation）, some Bi particles accumulated at the interface between Cu6 Sn5 layer and the solder.
