With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite...With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite(Jar)and schwertmannite(Sch)were biosynthesized using Acidithiobacillus ferrooxidans for the adsorption of REEs.Additionally,the adsorption capacities of Jar and Sch for La^(3+),Ce^(3+),Pr^(3+),Nd^(3+),Sm^(3+),Gd^(3+),Dy^(3+),and Y^(3+)in mine wastewater were improved by mechanical activation.XRD,FTIR,BET,and SEM-EDS analyses revealed that mechanical activation did not alter the phase of the material,but increased the amount of surface-OH and SO42−groups,as well as the specific surface area.This significantly enhanced the adsorption performance of Jar and Sch for REEs.The optimum adsorption time and pH were determined through batch adsorption experiments.Besides,the adsorption kinetics were studied and found to align well with the pseudo-second-order model.Furthermore,the thermodynamic parameters(ΔG^(Θ),ΔH^(Θ)andΔS^(Θ))and adsorption isotherms were analyzed.The results indicated that mechanically activated schwertmannite(M-Sch)exhibited superior adsorption performance for REEs compared to mechanically activated jarosite(M-Jar).Moreover,M-Sch was reusable and exhibited high adsorption efficiency of REEs in actual mine wastewater,exceeding 92%.展开更多
A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can ...A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can reach up to 95.9%,82.1%,68.3%,93.3%,82.3%,96.9%,98.3%and 95.6%,respectively,under the optimal condition in the leaching process.Aliquat 336 showed excellent extraction performance of iron in chloride-rich solution,and the maximum extraction efficiency can reach over 96%in one time extraction while the loss of other metals was less than 10%,under the condition of Aliquat 336 concentration(v/v)of 30%,aqueous-organic ratio of 1.0 and extraction time of 20 min.Furthermore,P204 can effectively extract the scandium while Al and most other REEs remain in the aqueous phase.This approach may provide a new insight for the recovery of valuable resources from red mud.展开更多
Rare earth element （REE） concentrations were measured by ICP-MS for groundwater collected from deep seated Taiyuan Fm limestone aquifer （from -400 to -530 m） in Renlou Coal Mine, northern Anhui Province, China. It...Rare earth element （REE） concentrations were measured by ICP-MS for groundwater collected from deep seated Taiyuan Fm limestone aquifer （from -400 to -530 m） in Renlou Coal Mine, northern Anhui Province, China. It can be concluded that the groundwater is warm （34.0-37.2 ℃） C1-Ca, Na type water with circum-neutral pH （7.35-8.28） and high total dissolved solids （TDS, 1 746-2 849 mg/L）. The groundwater exhibits heavy REEs enrichment relative to light REEs compared with Post Archean Average Shale （PAAS）, as well as their aquifer rocks （limestone）. The enrichment of REEs is considered to be controlled by terrigeneous materials （e.g. zircon） in aquifer rocks, whereas the fractionation of REEs is controlled by marine derived materials （e.g. calcite）, to a less extent, terrigeneous materials and inorganic complexation. The Ce anomalies normalized to PAAS and aquifer rocks are weak, which probably reflects the signature of the aquifer rock rather than redox conditions or pH. The similarities of REE patterns between groundwater and aquifer rocks imply that aquifer rocks play important roles in controlling the REE characteristics of groundwater, and then provide a probability for discrimination of groundwater sources by using REEs.展开更多
Phosphogypsum(PG)is a potential resource for rare earth elements(REEs).Several studies have been carried out on REE leaching from PG.However,few in-depth studies have investigated the kinetics of this leaching process...Phosphogypsum(PG)is a potential resource for rare earth elements(REEs).Several studies have been carried out on REE leaching from PG.However,few in-depth studies have investigated the kinetics of this leaching process.In this study,the leaching kinetics of REEs from PG in nitric acid at different temperatures were explored in depth.The experiments show that the maximum leaching recovery for ΣREE was 58.5%,75.9%and 83.4%at 30,60 and 80℃,respectively.Additionally,among La,Ce,Y and Nd,Y had the highest leaching rate.A new shrinking core model(SCM)based on the dissolution reaction of a cylindrical solid particle with interfacial transfer and diffusion across the product layer as the rate-controlling step was deduced and could well fit the leaching process of REEs from PG.The activation energies for the leaching of La,Ce,Y and Nd were determined on the basis of the new cylindrical SCM.In summary,the cylindrical SCM was a more suitable fitting model than the spherical SCM,and the interfacial transfer and diffusion across the product layer were the rate-controlling step for REE leaching from the PG sample.展开更多
The material sources and control factors of rare earth elemems （REEs） for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying （borehole number： ZK10-6）, Sichuan Province, South China...The material sources and control factors of rare earth elemems （REEs） for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying （borehole number： ZK10-6）, Sichuan Province, South China, were investigated. All samples were determined by inductively coupled plasma mass spectrometry （ICP-MS）. The chondrite-normalized distribution patterns of mudstone samples are uniform. All samples belong to the light rare earth element （LREE）-rich type and are enriched in LREEs relative to heavy rare earth elements （HREEs）. The distribution curves of REEs in mudstone are highly similar to Mount Emei basalt and the three periods of REEs enrichment correspond to three Mount Emei basalt eruption cycles in Longtan period. The results indicate that REE patterns are not controlled by materials from the seawater or land plants. The predominant sources of REEs are from terrigenous material as indicated by negative Eu anomaly. So, the sources of REEs are controlled by terrigenous material, and the Mount Emei basalt is the predominant source of terrigenous material. Thus, transgression-regression is another control factor of REEs enrichment.展开更多
The western Tianshan high-pressure(HP) metamorphic belt represents the paleosubduction mélange of paleozoic south Tianshan ocean between the Yili-central Tianshan and Tarim plates. High-pressure veins are extensi...The western Tianshan high-pressure(HP) metamorphic belt represents the paleosubduction mélange of paleozoic south Tianshan ocean between the Yili-central Tianshan and Tarim plates. High-pressure veins are extensively developed in this HP belt. Compared with normal mid-ocean ridge basalt(N-MORB), the high-pressure veins and host rocks are enriched in light rare earth elements(LREE) and incompatible elements. But high-pressure veins show a larger variation than host rocks in total REE abundance. On the trace element spidergram, all the samples are enriched in incompatible elements and show strong positive Pb anomaly relative to N-MORB. The array tendency lines of plots of the HP rocks have apparent slopes on diagram of m(Sr) vs m(Sr)/m(Zr), m(Li) vs m(Li)/m(Y) and (m(Ce)) vs m(Ce)/m(Pb), which indicates that the enrichment in LREE and incompatible elements relative to N-MORB of the HP-metamorphic rocks from western Tianshan is not attributed to magma evolution process of the protolith. High field strength elements, such as Nb, Ta, Ti, Zr and Hf, do not show negative anomaly relative to N-MORB, which is dissimilar to that of island arc basalts. Therefore, the enrichment in LREE and incompatible elements of the HP rocks is not attributed to the enrichment of the source of the protolith. The mass ratios of Rb to Ba, Ce to Pb, Nb to U and Ta to U of high-pressure veins and host rocks are intermediate of mid-ocean ridge basalt or oceanic island basalt and continental crust. The fluids in western Tianshan paleosubduction zones are mixtures of two sources, dehydration or devolatilization of host rocks and of subducted sediments.展开更多
Ningwu porphyrite-type iron deposits are located in Ningwu Mesozoic volcanic basin,which belongs to the middle and lower reaches of the Yangtze River metallogenic province.The volcanic rocks can be divided into Longwa...Ningwu porphyrite-type iron deposits are located in Ningwu Mesozoic volcanic basin,which belongs to the middle and lower reaches of the Yangtze River metallogenic province.The volcanic rocks can be divided into Longwangshan,Dawangshan,Gushan and Niangniangshan Formations from early to late.All these volcanic rocks are rich in alkali,and show the similar patterns in rare earth element(REE) distribution.However,some differences can be found in the trace elements and REE patterns.The study of petrology and REE geochemical characteristics shows that these rocks are derived from the underplating of the lithospheric mantle and are contaminated by crustal materials,undergo AFC process during the magmatic evolution.展开更多
The microstructure and Gd-rich phase evolution of as-cast AZ31-xGd(x=0,1.5 wt.%,2.0 wt.%and 2.5 wt.%)magnesium alloys during semi-solid isothermal heat treatment were investigated deeply in the present work.Results sh...The microstructure and Gd-rich phase evolution of as-cast AZ31-xGd(x=0,1.5 wt.%,2.0 wt.%and 2.5 wt.%)magnesium alloys during semi-solid isothermal heat treatment were investigated deeply in the present work.Results showed that the lamellar(Mg,Al)3Gd phases transformed into the particle-like Al2Gd phases in AZ31 magnesium alloys with Gd addition during semi-solid isothermal heat treatment,leading to yielding more sphericalα-Mg grains.When Gd content is 2.0 wt.%,the size of semi-solid spherical grains reaches the minimum.The main mechanism of grain refinement lies in the remelting of dendritic branches as well as the auxiliary effect of a small number of Al2Gd particles as grain refining inoculants.Meanwhile,Al2Gd particles enriched at the solid-liquid interfaces can remarkably retard the growth rate ofα-Mg grains.A reduction of deformation resistance has been successfully achieved in AZ31-2.0Gd magnesium alloy after semi-solid isothermal heat treatment,which shows a moderate compressive deformation resistance(230 MPa),comparing to the as-cast AZ31 magnesium alloy(280 MPa)and semi-solid AZ31 magnesium alloy(209 MPa).展开更多
A yttrium-containing high-temperature titanium alloy(Ti-6Al-2.7Sn-4Zr-0.4Mo-0.45Si-0.1Y, mass fraction, %) has been additively manufactured using selective electron beam melting(SEBM). The resulting microstructure and...A yttrium-containing high-temperature titanium alloy(Ti-6Al-2.7Sn-4Zr-0.4Mo-0.45Si-0.1Y, mass fraction, %) has been additively manufactured using selective electron beam melting(SEBM). The resulting microstructure and textures were studied using scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and electron backscattered diffraction(EBSD) and compared with the conventionally manufactured form. A notable distinct difference of microstructures is that additive manufacturing by SEBM enables homogeneous precipitation of fine Y2O3 dispersoids in the size range of 50-250 nm throughout the as-fabricated alloy, despite the presence of just trace levels of oxygen(7×10-4, mass fraction) and yttrium(10-3, mass fraction) in the alloy. In contrast, the conventionally manufactured alloy shows inhomogeneously distributed coarse Y2O3 precipitates, including cracked or debonded Y2O3 particles.展开更多
The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is...The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h,the Cu3Sn IMC is then obtained. With increasing aging time,the scalloped Cu6Sn5 structure changes to a plate structure. The Cu3Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce (only 0.1%,mass fraction) into the Sn-3.0Ag-0.5Cu solder alloy,the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5,the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.展开更多
The hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic pro...The hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic properties of powders were respectively studied by means of X-ray diffractometer (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450–850 °C with different mole ratio of Nd to Ba (0.1–1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1–3) and calcination temperature of 850 °C for 1 h, M-type BaNd x Fe12?x O19(x=0.1?1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m?1 at x=1, which is far greater than that of barium permanent ferrite (BaFe12O19).展开更多
基金Project(2022YFC2105300) supported by the National Key Research and Development Program of ChinaProject(52274288) supported by the National Natural Science Foundation of China。
文摘With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite(Jar)and schwertmannite(Sch)were biosynthesized using Acidithiobacillus ferrooxidans for the adsorption of REEs.Additionally,the adsorption capacities of Jar and Sch for La^(3+),Ce^(3+),Pr^(3+),Nd^(3+),Sm^(3+),Gd^(3+),Dy^(3+),and Y^(3+)in mine wastewater were improved by mechanical activation.XRD,FTIR,BET,and SEM-EDS analyses revealed that mechanical activation did not alter the phase of the material,but increased the amount of surface-OH and SO42−groups,as well as the specific surface area.This significantly enhanced the adsorption performance of Jar and Sch for REEs.The optimum adsorption time and pH were determined through batch adsorption experiments.Besides,the adsorption kinetics were studied and found to align well with the pseudo-second-order model.Furthermore,the thermodynamic parameters(ΔG^(Θ),ΔH^(Θ)andΔS^(Θ))and adsorption isotherms were analyzed.The results indicated that mechanically activated schwertmannite(M-Sch)exhibited superior adsorption performance for REEs compared to mechanically activated jarosite(M-Jar).Moreover,M-Sch was reusable and exhibited high adsorption efficiency of REEs in actual mine wastewater,exceeding 92%.
基金Project(21707167)supported by the Natural Science Foundation of China
文摘A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can reach up to 95.9%,82.1%,68.3%,93.3%,82.3%,96.9%,98.3%and 95.6%,respectively,under the optimal condition in the leaching process.Aliquat 336 showed excellent extraction performance of iron in chloride-rich solution,and the maximum extraction efficiency can reach over 96%in one time extraction while the loss of other metals was less than 10%,under the condition of Aliquat 336 concentration(v/v)of 30%,aqueous-organic ratio of 1.0 and extraction time of 20 min.Furthermore,P204 can effectively extract the scandium while Al and most other REEs remain in the aqueous phase.This approach may provide a new insight for the recovery of valuable resources from red mud.
基金Project(40873015) supported by the National Natural Science Foundation of ChinaProject(08010302062) supported by the Eleventh Five-year Scientific and Technological Program of Anhui Province,China
文摘Rare earth element （REE） concentrations were measured by ICP-MS for groundwater collected from deep seated Taiyuan Fm limestone aquifer （from -400 to -530 m） in Renlou Coal Mine, northern Anhui Province, China. It can be concluded that the groundwater is warm （34.0-37.2 ℃） C1-Ca, Na type water with circum-neutral pH （7.35-8.28） and high total dissolved solids （TDS, 1 746-2 849 mg/L）. The groundwater exhibits heavy REEs enrichment relative to light REEs compared with Post Archean Average Shale （PAAS）, as well as their aquifer rocks （limestone）. The enrichment of REEs is considered to be controlled by terrigeneous materials （e.g. zircon） in aquifer rocks, whereas the fractionation of REEs is controlled by marine derived materials （e.g. calcite）, to a less extent, terrigeneous materials and inorganic complexation. The Ce anomalies normalized to PAAS and aquifer rocks are weak, which probably reflects the signature of the aquifer rock rather than redox conditions or pH. The similarities of REE patterns between groundwater and aquifer rocks imply that aquifer rocks play important roles in controlling the REE characteristics of groundwater, and then provide a probability for discrimination of groundwater sources by using REEs.
基金Project(51904104) supported by the National Natural Science Foundation of ChinaProject(2020JJ5174) supported by the Natural Science Foundation of Hunan Province,China+2 种基金Project(2019M662780) supported by China Postdoctoral Science FoundationProject(19C0746) supported by Scientific Research Fund of Hunan Provincial Education Department,ChinaProject(2021-2843) supported by College Student Innovation and Entrepreneurship Training Program of Hunan Province,China。
文摘Phosphogypsum(PG)is a potential resource for rare earth elements(REEs).Several studies have been carried out on REE leaching from PG.However,few in-depth studies have investigated the kinetics of this leaching process.In this study,the leaching kinetics of REEs from PG in nitric acid at different temperatures were explored in depth.The experiments show that the maximum leaching recovery for ΣREE was 58.5%,75.9%and 83.4%at 30,60 and 80℃,respectively.Additionally,among La,Ce,Y and Nd,Y had the highest leaching rate.A new shrinking core model(SCM)based on the dissolution reaction of a cylindrical solid particle with interfacial transfer and diffusion across the product layer as the rate-controlling step was deduced and could well fit the leaching process of REEs from PG.The activation energies for the leaching of La,Ce,Y and Nd were determined on the basis of the new cylindrical SCM.In summary,the cylindrical SCM was a more suitable fitting model than the spherical SCM,and the interfacial transfer and diffusion across the product layer were the rate-controlling step for REE leaching from the PG sample.
基金Project(40839910) supported by the National Natural Science Foundation of China
文摘The material sources and control factors of rare earth elemems （REEs） for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying （borehole number： ZK10-6）, Sichuan Province, South China, were investigated. All samples were determined by inductively coupled plasma mass spectrometry （ICP-MS）. The chondrite-normalized distribution patterns of mudstone samples are uniform. All samples belong to the light rare earth element （LREE）-rich type and are enriched in LREEs relative to heavy rare earth elements （HREEs）. The distribution curves of REEs in mudstone are highly similar to Mount Emei basalt and the three periods of REEs enrichment correspond to three Mount Emei basalt eruption cycles in Longtan period. The results indicate that REE patterns are not controlled by materials from the seawater or land plants. The predominant sources of REEs are from terrigenous material as indicated by negative Eu anomaly. So, the sources of REEs are controlled by terrigenous material, and the Mount Emei basalt is the predominant source of terrigenous material. Thus, transgression-regression is another control factor of REEs enrichment.
基金Preoject(2001CB409803) supported by the National Key Fundamental Research and Development Program of China
文摘The western Tianshan high-pressure(HP) metamorphic belt represents the paleosubduction mélange of paleozoic south Tianshan ocean between the Yili-central Tianshan and Tarim plates. High-pressure veins are extensively developed in this HP belt. Compared with normal mid-ocean ridge basalt(N-MORB), the high-pressure veins and host rocks are enriched in light rare earth elements(LREE) and incompatible elements. But high-pressure veins show a larger variation than host rocks in total REE abundance. On the trace element spidergram, all the samples are enriched in incompatible elements and show strong positive Pb anomaly relative to N-MORB. The array tendency lines of plots of the HP rocks have apparent slopes on diagram of m(Sr) vs m(Sr)/m(Zr), m(Li) vs m(Li)/m(Y) and (m(Ce)) vs m(Ce)/m(Pb), which indicates that the enrichment in LREE and incompatible elements relative to N-MORB of the HP-metamorphic rocks from western Tianshan is not attributed to magma evolution process of the protolith. High field strength elements, such as Nb, Ta, Ti, Zr and Hf, do not show negative anomaly relative to N-MORB, which is dissimilar to that of island arc basalts. Therefore, the enrichment in LREE and incompatible elements of the HP rocks is not attributed to the enrichment of the source of the protolith. The mass ratios of Rb to Ba, Ce to Pb, Nb to U and Ta to U of high-pressure veins and host rocks are intermediate of mid-ocean ridge basalt or oceanic island basalt and continental crust. The fluids in western Tianshan paleosubduction zones are mixtures of two sources, dehydration or devolatilization of host rocks and of subducted sediments.
基金Project(2011BAB04D01) supported by the National Science and Technology Support Program of China
文摘Ningwu porphyrite-type iron deposits are located in Ningwu Mesozoic volcanic basin,which belongs to the middle and lower reaches of the Yangtze River metallogenic province.The volcanic rocks can be divided into Longwangshan,Dawangshan,Gushan and Niangniangshan Formations from early to late.All these volcanic rocks are rich in alkali,and show the similar patterns in rare earth element(REE) distribution.However,some differences can be found in the trace elements and REE patterns.The study of petrology and REE geochemical characteristics shows that these rocks are derived from the underplating of the lithospheric mantle and are contaminated by crustal materials,undergo AFC process during the magmatic evolution.
基金Project(20171BAB206005)supported by the Natural Science Foundation of Jiangxi Province,ChinaProject(20153BCB23023)supported by the Training Program Foundation for Young Scientists of Jiangxi Province,ChinaProject(51961026)supported by the National Natural Science Foundation of China。
文摘The microstructure and Gd-rich phase evolution of as-cast AZ31-xGd(x=0,1.5 wt.%,2.0 wt.%and 2.5 wt.%)magnesium alloys during semi-solid isothermal heat treatment were investigated deeply in the present work.Results showed that the lamellar(Mg,Al)3Gd phases transformed into the particle-like Al2Gd phases in AZ31 magnesium alloys with Gd addition during semi-solid isothermal heat treatment,leading to yielding more sphericalα-Mg grains.When Gd content is 2.0 wt.%,the size of semi-solid spherical grains reaches the minimum.The main mechanism of grain refinement lies in the remelting of dendritic branches as well as the auxiliary effect of a small number of Al2Gd particles as grain refining inoculants.Meanwhile,Al2Gd particles enriched at the solid-liquid interfaces can remarkably retard the growth rate ofα-Mg grains.A reduction of deformation resistance has been successfully achieved in AZ31-2.0Gd magnesium alloy after semi-solid isothermal heat treatment,which shows a moderate compressive deformation resistance(230 MPa),comparing to the as-cast AZ31 magnesium alloy(280 MPa)and semi-solid AZ31 magnesium alloy(209 MPa).
基金Projects(2014KTZB01-02-03,2014KTZB01-02-04)supported by Shaanxi Science and Technology Coordination and Innovation Program,ChinaProject(DP120101672)supported by Australian Research Council(ARC)Discovery Grant,ARC Centre of Excellence for Design in Light Metals,Australia
文摘A yttrium-containing high-temperature titanium alloy(Ti-6Al-2.7Sn-4Zr-0.4Mo-0.45Si-0.1Y, mass fraction, %) has been additively manufactured using selective electron beam melting(SEBM). The resulting microstructure and textures were studied using scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and electron backscattered diffraction(EBSD) and compared with the conventionally manufactured form. A notable distinct difference of microstructures is that additive manufacturing by SEBM enables homogeneous precipitation of fine Y2O3 dispersoids in the size range of 50-250 nm throughout the as-fabricated alloy, despite the presence of just trace levels of oxygen(7×10-4, mass fraction) and yttrium(10-3, mass fraction) in the alloy. In contrast, the conventionally manufactured alloy shows inhomogeneously distributed coarse Y2O3 precipitates, including cracked or debonded Y2O3 particles.
基金Project(06GK2002) supported by the Major Project of Hunan Provincial Science and Technology Development Strategy
文摘The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h,the Cu3Sn IMC is then obtained. With increasing aging time,the scalloped Cu6Sn5 structure changes to a plate structure. The Cu3Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce (only 0.1%,mass fraction) into the Sn-3.0Ag-0.5Cu solder alloy,the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5,the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.
文摘The hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic properties of powders were respectively studied by means of X-ray diffractometer (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450–850 °C with different mole ratio of Nd to Ba (0.1–1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1–3) and calcination temperature of 850 °C for 1 h, M-type BaNd x Fe12?x O19(x=0.1?1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m?1 at x=1, which is far greater than that of barium permanent ferrite (BaFe12O19).
