Al-Ti diffusion couples were made by embedded technology and treated at the temperature between the melting points of Al and Ti. The microstructure evolution and growth mechanism of the Al-Ti DRZ were investigated. Th...Al-Ti diffusion couples were made by embedded technology and treated at the temperature between the melting points of Al and Ti. The microstructure evolution and growth mechanism of the Al-Ti DRZ were investigated. The result shows that the DRZ, the mixture of TiAl3 and Al, grows layer by layer along their chemical equilibrium zone. In the course, the growth interface moves toward the aluminum side. TiAl3 is the only new phase which forms earliest in the course of heat-treatment. The growth mechanism of the DRZ changes after the phase transition of titanium. Before the phase transition of titanium, the growth of the DRZ is controlled by the dissolution speed of the titanium to the molten aluminum, while after the phase transition of titanium, the growth is controlled by the chemical reaction speed of Al and Ti atoms, and consequently, its growth rate is greatly increased.展开更多
The carbon nanotubes(CNTs) reinforced Al-Cu matrix composites were prepared by hot pressing sintering and hot rolling, and the effects of Cu content on the interfacial reaction between Al and CNTs, the precipitation b...The carbon nanotubes(CNTs) reinforced Al-Cu matrix composites were prepared by hot pressing sintering and hot rolling, and the effects of Cu content on the interfacial reaction between Al and CNTs, the precipitation behavior of Cu-containing precipitates, and the resultant mechanical properties of the composites were systematically investigated. The results showed that the increase of Cu content can not only increase the number and size of Cu-containing precipitate generated during the composite fabrication processes, but also promote the interfacial reaction between CNTs and Al matrix, leading to the intensified conversion of CNTs into Al_(4)C_(3). As a result, the composite containing 1 wt.% Cu possesses the highest strength, elastic modulus and hardness among all composites, due to the maintenance of the original structure of CNTs. Moreover, the increase of Cu content can change the dominant strengthening mechanisms for the enhanced strength of the fabricated composites.展开更多
The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compo...The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compounds(IMC)at the AuSn20/Ni soldering interface were investigated by scanning electron microscopy(SEM)and electron probe microanalysis(EPMA).The results show that,the(Ni,Au)3Sn2phases are formed at the AuSn20/Ni interface after soldering at583K.The thickness l of the IMC layer monotonically increases with increasing annealing time t according to the relationship l=k(t/t0)n,where the exponent n is0.527,0.476and0.471for393,433and473K annealing,respectively.This indicates that the volume diffusion contributes to the growth of the IMC layer at the AuSn20/Ni interface at solid-sate temperature.The pre-exponential factor K0=1.23×10?7m2/s and the activation enthalpy QK=81.8kJ/mol are obtained from the results of the parabolic coefficient K by a least-squares method.展开更多
Harvesting the promising high energy density of advanced electrode materials in lithium-ion batteries is critically dependent on a mechanistic understanding on how the materials function and degrade along with the bat...Harvesting the promising high energy density of advanced electrode materials in lithium-ion batteries is critically dependent on a mechanistic understanding on how the materials function and degrade along with the battery cycling.Here,we tracked phase transformations during(de)lithiation of Sb_(2)Se_(3) single crystals using in situ high-resolution transmission electron microscopy(HRTEM)technique,and revealed electro-chemo-mechanical evolution at the reaction interface.The effect of this electro-chemo-mechanical coupling has a complicated interplay on the lithiation kinetics and causes various types of defects at the reaction front,including dislocation dipoles,antiphase boundaries,and cracks.In return,the formed cracks and related defects build a path for fast diffusion of lithium ions and trigger a highly anisotropic lithiation at the twisted reaction front,giving rise to the formation of presumably "dead" Sb_(2)Se_(3) nanodomains in amorphous Li_(x)Sb_(2)Se_(3).The detailed mechanistic understanding may facilitate the rational design of high-capacity electrode materials for battery applications.展开更多
基金Project (ZR2011EL023) supported by the Natural Science Foundation of Shandong Province,ChinaProject (12CX04057A) supported by the Fundamental Research Funds for the Central Universities,China
文摘Al-Ti diffusion couples were made by embedded technology and treated at the temperature between the melting points of Al and Ti. The microstructure evolution and growth mechanism of the Al-Ti DRZ were investigated. The result shows that the DRZ, the mixture of TiAl3 and Al, grows layer by layer along their chemical equilibrium zone. In the course, the growth interface moves toward the aluminum side. TiAl3 is the only new phase which forms earliest in the course of heat-treatment. The growth mechanism of the DRZ changes after the phase transition of titanium. Before the phase transition of titanium, the growth of the DRZ is controlled by the dissolution speed of the titanium to the molten aluminum, while after the phase transition of titanium, the growth is controlled by the chemical reaction speed of Al and Ti atoms, and consequently, its growth rate is greatly increased.
基金The financial supports from the National Natural Science Foundation of China (Nos. 52004101 and 52071269)the Chinese Postdoctoral Science Foundation (No. 2020T130246)+2 种基金the Fund of the State Key Laboratory of Solidification Processing in NWPU, China (No. SKLSP202121)the Guangdong Basic and Applied Basic Research Foundation, China (No. 2020A1515110621)the Fundamental Research Funds for the Central Universities, China (No. 11620345)。
文摘The carbon nanotubes(CNTs) reinforced Al-Cu matrix composites were prepared by hot pressing sintering and hot rolling, and the effects of Cu content on the interfacial reaction between Al and CNTs, the precipitation behavior of Cu-containing precipitates, and the resultant mechanical properties of the composites were systematically investigated. The results showed that the increase of Cu content can not only increase the number and size of Cu-containing precipitate generated during the composite fabrication processes, but also promote the interfacial reaction between CNTs and Al matrix, leading to the intensified conversion of CNTs into Al_(4)C_(3). As a result, the composite containing 1 wt.% Cu possesses the highest strength, elastic modulus and hardness among all composites, due to the maintenance of the original structure of CNTs. Moreover, the increase of Cu content can change the dominant strengthening mechanisms for the enhanced strength of the fabricated composites.
基金Project(JPPT-125-GH-039)supported by the Ministry of Science and Technology of ChinaProject(Z109021567)supported by Fundamental Research Funds for the Central Universities,China
文摘The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compounds(IMC)at the AuSn20/Ni soldering interface were investigated by scanning electron microscopy(SEM)and electron probe microanalysis(EPMA).The results show that,the(Ni,Au)3Sn2phases are formed at the AuSn20/Ni interface after soldering at583K.The thickness l of the IMC layer monotonically increases with increasing annealing time t according to the relationship l=k(t/t0)n,where the exponent n is0.527,0.476and0.471for393,433and473K annealing,respectively.This indicates that the volume diffusion contributes to the growth of the IMC layer at the AuSn20/Ni interface at solid-sate temperature.The pre-exponential factor K0=1.23×10?7m2/s and the activation enthalpy QK=81.8kJ/mol are obtained from the results of the parabolic coefficient K by a least-squares method.
基金supported by the National Key R&D Program of China(2018YFB1304902)the National Natural Science Foundation of China(11904372,U1813211,and 12004034)+2 种基金Beijing Institute of Technology Research Fund Program for Young ScholarsBeijing Institute of Technology Laboratory Research Project(2019BITSYA03)China Postdoctoral Science Foundation Funded Project(2021M690386)。
文摘Harvesting the promising high energy density of advanced electrode materials in lithium-ion batteries is critically dependent on a mechanistic understanding on how the materials function and degrade along with the battery cycling.Here,we tracked phase transformations during(de)lithiation of Sb_(2)Se_(3) single crystals using in situ high-resolution transmission electron microscopy(HRTEM)technique,and revealed electro-chemo-mechanical evolution at the reaction interface.The effect of this electro-chemo-mechanical coupling has a complicated interplay on the lithiation kinetics and causes various types of defects at the reaction front,including dislocation dipoles,antiphase boundaries,and cracks.In return,the formed cracks and related defects build a path for fast diffusion of lithium ions and trigger a highly anisotropic lithiation at the twisted reaction front,giving rise to the formation of presumably "dead" Sb_(2)Se_(3) nanodomains in amorphous Li_(x)Sb_(2)Se_(3).The detailed mechanistic understanding may facilitate the rational design of high-capacity electrode materials for battery applications.
