In this paper, the Co-free hydrogen storage alloys with the nominal compositions of La0.75R0.05Mg0.20Ni3.40Al0.10（R = La, Nd and Sm） were prepared by induction melting, and then the phase structure and electrochemic...In this paper, the Co-free hydrogen storage alloys with the nominal compositions of La0.75R0.05Mg0.20Ni3.40Al0.10（R = La, Nd and Sm） were prepared by induction melting, and then the phase structure and electrochemical properties of these alloys were comparatively investigated. It is found that the alloys mainly consist of（La, Mg）2Ni7phase, La Ni5 phase and（La, Mg）5Ni19phase.Refinement results further show that Nd substitution for La remarkably promotes the formation of La Ni5 phase, while Sm is beneficial for the formation of（La, Mg）5Ni19phase.At discharge current density of 1,875 m A g-1, the highrate dischargeability（HRD） of alloy electrodes increases by 13.9 % and 6.5 % with La substituted by Nd and Sm,respectively. The electrochemical kinetic measurements reveal that the exchange current density（I0）, charge transfer resistance（R） and hydrogen diffusion coefficient（D） for the alloy electrode are all facilitated with Nd and Sm partial substitution for La. Subsequently, a linear correlation between the HRD1875 and the corresponding I0/D is found.展开更多
During faunal studies of psammophilic ciliates along the coast of Qingdao, China, several marine karyorelictean species were isolated. Among them,four species within the genus Remanella were investigated, including tw...During faunal studies of psammophilic ciliates along the coast of Qingdao, China, several marine karyorelictean species were isolated. Among them,four species within the genus Remanella were investigated, including two species new to science:i.e., R. rugosa, Remanella elongata sp. nov.,Remanella aposinica sp. nov.,and R.unicorpusculata. Remanella rugosa has been reported several times, but this study is the first to provide detailed morphological characters and phylogenetics. Remanella elongata sp. nov. can be distinguished from its congeners by the presence of complex cortical granules, fewer macronuclei, and longer body size. Remanella aposinica sp. nov.differs from its congeners by having 14–17 right lateral ciliary rows and 24–37 dikinetids of intrabuccal kinety. Poorly known Remanella rugosa var. unicorpusculata(Kahl, 1933) Foissner, 1996should be elevated from subspecies to species level,Remanella unicorpusculata(Foissner, 1996) stat.nov., based on detailed redescriptions with statistical data, living morphology, infraciliature, and species definitions. Small subunit(SSU) rDNA was sequenced for the four species, and phylogenetic analysis revealed that all known taxa in Remanella formed the outline branch to the genus Loxodes with moderate to high bootstrap support among Remanella lineages.展开更多
Two colepid ciliates, Coleps amphacanthus Ehrenberg, 1833 and Levicoleps biwae jejuensis Chen et al., 2016, were first recorded in China. Their living morphology, infraciliature and small subunit （SSU） rRNA gene seq...Two colepid ciliates, Coleps amphacanthus Ehrenberg, 1833 and Levicoleps biwae jejuensis Chen et al., 2016, were first recorded in China. Their living morphology, infraciliature and small subunit （SSU） rRNA gene sequences were determined using standard methods. The improved diagnosis of Coleps amphacanthus is as follows： cell size about 100x 50 pm in vivo, barrel-shaped; 22-28 ciliary rows each composed of about 14-21 monokinetids and two perioral dikinetids; 5-10 caudal cilia; and one terminal contractile vacuole. Levicoleps biwae jejuensis was also investigated, with an improved diagnosis given based on previous and present work. The phylogenetic analyses based on SSU rRNA gene sequences revealed that all Coleps species were grouped together, except for Coleps amphacanthus, which was grouped into a clade of the genus Levicoleps.展开更多
The deformation behavior and microstructure of the Zr50Ti50 alloy in β phase field were investigated by isothermal compression tests at temperatures ranging from 700 to 850 °C and strain rates ranging from 0.001...The deformation behavior and microstructure of the Zr50Ti50 alloy in β phase field were investigated by isothermal compression tests at temperatures ranging from 700 to 850 °C and strain rates ranging from 0.001 to 1 s?1. The flow curves exhibited typical flow softening. The initial discontinuous yielding behavior was observed at higher strain rates, which was not found in other traditional Zr alloys. The apparent deformation activation energy was calculated to be 103 kJ/mol and constitutive equationdescribing the flow stress as a function of the strain rate and deformation temperature was proposed. The analysis indicated that the hot deformation mechanism was mainly dominated by dynamic recovery. However, dynamic recrystallization was delayed by dynamic recovery. Thereafter, the processing map was calculated to evaluate the efficiency of the forging process at the temperatures and strain rates investigated and to optimize processing parameters of hot deformation. The optimum processing parameters were found to be 830?850 °C and 0.56?1 s?1 for hot the deformation of Zr50Ti50 alloy in the β phase region.展开更多
Many amorphous alloys have been developed to date,but the low plasticity has limited their application.To achieve an amorphous alloy with high plasticity,a series of(Ti_(40)Zr_(25)Cu_(9)Ni_(8) Be_(18))_(100-x)TM_(x)(x...Many amorphous alloys have been developed to date,but the low plasticity has limited their application.To achieve an amorphous alloy with high plasticity,a series of(Ti_(40)Zr_(25)Cu_(9)Ni_(8) Be_(18))_(100-x)TM_(x)(x=0,1,2,3,4 at.%,TM=Nb,Y)alloys were designed to study the influence of Nb and Y addition on the plasticity.The amorphous samples were prepared using the vacuum melting and copper mold casting process.The microstructures,glass forming ability and mechanical properties of the alloys were investigated by X-ray diffractometry(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),depth-sensitive nanoindentation,and uniaxial compressive test.The plasticity of different bulk amorphous alloys was investigated by measuring the plastic deformation energy(PDE)during loading.The relationship between the PDE value and plasticity in bulk amorphous alloys was explored.Results show that Nb addition decreases the PDE value and promotes the generation of multiple shear bands,which significantly increases the fracture strength and plasticity,while the addition of Y element reduces the fracture strength and plastic strain of the alloy.展开更多
Thermal expansion is a common phenomenon in both metals and alloys, which is important for metallic material applications in modern industry, especially in nuclear and aerospace industries. A lower thermal expansion c...Thermal expansion is a common phenomenon in both metals and alloys, which is important for metallic material applications in modern industry, especially in nuclear and aerospace industries. A lower thermal expansion coefficient may cause lower thermal stress and higher accuracy. A new Zr-based alloy is developed and presented.The XRD diffraction results demonstrate that only a close-packed hexagonal phase（α or α＇ phase） exists in the microstructure. The thermal expansion and mechanical properties are studied. According to the experimental results, the new Zr-based alloy presents a low thermal expansion coefficient and good mechanical properties.Also,its thermal expansion coefficient is stable through solution treatment.展开更多
An outer ring of 29320 self-aliging roller bearing was used in an experimental study on the casting of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5) amorphous alloy.Numerical simulations of mold filling and solidification p...An outer ring of 29320 self-aliging roller bearing was used in an experimental study on the casting of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5) amorphous alloy.Numerical simulations of mold filling and solidification processes were carried out to determine the velocity fields and temperature fields of the alloy melt during mold filling process as well as the temperature fields and temperature gradient fields in the course of the solidification.According to the results,a cast with a complete shape can be obtained at 1200℃under the condition that the cooling rate is greater than the critical cooling rate.The ring-shaped part with a thickness of 25 mm,an equivalent diameter of 22 mm,and a mass of 1.32 kg was prepared by gravity casting in a copper mold.X-ray diffraction and differential scanning calorimetry data revealed that the produced cast had the amorphous structure.展开更多
An Al-Mg-Si-Cu-Fe alloy was solid-solution treated at 560℃ for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temper...An Al-Mg-Si-Cu-Fe alloy was solid-solution treated at 560℃ for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temperatures. The microstructure and mechanical properties of the rolled alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and tensile testing. For the water-quenched alloys, the peak tensile strength and elongation occurred at a rolling temperature of 180℃. For the furnace-cooled alloys, the tensile strength decreased initially, until the rolling temperature of 420℃, and then increased;the elongation increased consistently with increasing rolling temperature. The effects of grain boundary hardening and dislocation hardening on the mechanical properties of these rolled alloys decreased with increases in rolling temperature. The mechanical properties of the 180℃ rolling water-quenched alloy were also improved by the presence ofβ″phase. Above 420℃, the effect of solid-solution hardening on the mechanical properties of the rolled alloys increased with increases in rolling temperature.展开更多
ZrO2 dispersion-strengthened Q345 steel with different ZrO2 contents（0%, 0.5% and 1.2%, mass fraction） was fabricated through combining middle frequency induction furnace melting and cored-wire injection technologie...ZrO2 dispersion-strengthened Q345 steel with different ZrO2 contents（0%, 0.5% and 1.2%, mass fraction） was fabricated through combining middle frequency induction furnace melting and cored-wire injection technologies. The microstructure and fracture surface morphology of ZrO2 dispersion-strengthened Q345 steel in casting, normalizing and quenching states were observed using optical microscopy, scanning electron microscopy and transmission electron microscopy. Also, strengthening and fracture mechanisms of the alloys were analyzed. Results showed that the dispersed ZrO2 particles added into Q345 matrix significantly enhanced its strength, and the main strengthening mechanism was the formation of dislocation cells and pinning effect caused by the addition of ZrO2 particles. Apart from that, the hard martensite phase, grain refinement and high ZrO2 particles content also played important roles in strengthening effect. Furthermore, the nanoindentation was also performed to further reveal the strengthening effect and mechanism of dispersed ZrO2 particles in Q345 steel. Results showed that the hardness of ZrO2 dispersion-strengthened Q345 steel increased with the increase of ZrO2 content.展开更多
Understanding the flow characteristics of amorphous metal melts is important for casting and molding processes.Fluidity of Zr-based amorphous metal melts was determined by using a self-designed apparatus.Phase analysi...Understanding the flow characteristics of amorphous metal melts is important for casting and molding processes.Fluidity of Zr-based amorphous metal melts was determined by using a self-designed apparatus.Phase analysis demonstrated that the fluidity test samples were fuUy amorphous structure.The onset crystallization temperature significantly moved toward high temperature with the increases of casting temperature,which improved the glass-forming ability and thermal stability of Zr-based amorphous metal.Fluidity test results demonstrated that the fluidity length increased monotonically with the increases of temperature,pressure,and runner diameter.By identifying the types and quantities of the defect in castings,it could conclude that smooth filling processes occurred under appropriate conditions.Experimental results indicated that the flow behavior of the Zr-based amorphous metal melts strongly depended on the casting temperature and equivalent thickness.Constitutive equation based on Newton's law of heat exchange and Rayleigh rule was established to'evaluate the fluidity of Zr-based amorphous metal melts.Theoretical calculations and experimental tests were basically coincided with each other.The determined optimal casting temperatures and equivalent thicknesses were adopted to successfully fabricate a series of fully shaped castings through gravity casting.展开更多
A significant refinement of the microstructure of structural NiTi alloy was achieved through a combination of Al addition and fabrication by suction casting.This is attributed to the change from a layer-by-layer to vo...A significant refinement of the microstructure of structural NiTi alloy was achieved through a combination of Al addition and fabrication by suction casting.This is attributed to the change from a layer-by-layer to volume solidification mode with Al content increasing,which causes a change in grain shape from columnar to equiaxed.Furthermore,when compared with conventional casting,suction casting optimizes the microstructure of the alloy by refining the grain size and ensuring a homogeneous distribution of Ti2 Ni and Ni_(2)TiAl phases.The high cooling rate of suction casting also delays the formation ofβ'-Ni_(2)TiAl phase.Finally,this fine microstructure and uniform distribution of intermetallic phases result in the ultimate compressive strength of up to 2463.7 MPa,representing an improvement of 370 MPa over conventionally cast NiTi-Al alloy.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51171165 and 21303157)the Natural Science Foundation of Hebei Province (Nos. B2012203027, B2012203104, and B2014203114)+1 种基金the China Postdoctoral Science Foundation Project (No. 2013M541201)the Research Fund for the Doctoral Program of Higher Education of China (No. 20131333120008)
文摘In this paper, the Co-free hydrogen storage alloys with the nominal compositions of La0.75R0.05Mg0.20Ni3.40Al0.10（R = La, Nd and Sm） were prepared by induction melting, and then the phase structure and electrochemical properties of these alloys were comparatively investigated. It is found that the alloys mainly consist of（La, Mg）2Ni7phase, La Ni5 phase and（La, Mg）5Ni19phase.Refinement results further show that Nd substitution for La remarkably promotes the formation of La Ni5 phase, while Sm is beneficial for the formation of（La, Mg）5Ni19phase.At discharge current density of 1,875 m A g-1, the highrate dischargeability（HRD） of alloy electrodes increases by 13.9 % and 6.5 % with La substituted by Nd and Sm,respectively. The electrochemical kinetic measurements reveal that the exchange current density（I0）, charge transfer resistance（R） and hydrogen diffusion coefficient（D） for the alloy electrode are all facilitated with Nd and Sm partial substitution for La. Subsequently, a linear correlation between the HRD1875 and the corresponding I0/D is found.
基金supported by the National Natural Science Foundation of China (32030015, 31961123002,32111530116)King Saud University,Saudi Arabia (RSP2022R7)+2 种基金Fundamental Research Funds for the Central Universities to Y.Y.(202141007)European Community H2020-MSCA-RISE 2019(872767)Young Taishan Scholar Program of Shandong Province。
文摘During faunal studies of psammophilic ciliates along the coast of Qingdao, China, several marine karyorelictean species were isolated. Among them,four species within the genus Remanella were investigated, including two species new to science:i.e., R. rugosa, Remanella elongata sp. nov.,Remanella aposinica sp. nov.,and R.unicorpusculata. Remanella rugosa has been reported several times, but this study is the first to provide detailed morphological characters and phylogenetics. Remanella elongata sp. nov. can be distinguished from its congeners by the presence of complex cortical granules, fewer macronuclei, and longer body size. Remanella aposinica sp. nov.differs from its congeners by having 14–17 right lateral ciliary rows and 24–37 dikinetids of intrabuccal kinety. Poorly known Remanella rugosa var. unicorpusculata(Kahl, 1933) Foissner, 1996should be elevated from subspecies to species level,Remanella unicorpusculata(Foissner, 1996) stat.nov., based on detailed redescriptions with statistical data, living morphology, infraciliature, and species definitions. Small subunit(SSU) rDNA was sequenced for the four species, and phylogenetic analysis revealed that all known taxa in Remanella formed the outline branch to the genus Loxodes with moderate to high bootstrap support among Remanella lineages.
基金Foundation items： This project was supported by the Natural Science Foundation of China （31572230） and the Ningbo Natural Science Foundation （2015A610263, 2015A610264）
文摘Two colepid ciliates, Coleps amphacanthus Ehrenberg, 1833 and Levicoleps biwae jejuensis Chen et al., 2016, were first recorded in China. Their living morphology, infraciliature and small subunit （SSU） rRNA gene sequences were determined using standard methods. The improved diagnosis of Coleps amphacanthus is as follows： cell size about 100x 50 pm in vivo, barrel-shaped; 22-28 ciliary rows each composed of about 14-21 monokinetids and two perioral dikinetids; 5-10 caudal cilia; and one terminal contractile vacuole. Levicoleps biwae jejuensis was also investigated, with an improved diagnosis given based on previous and present work. The phylogenetic analyses based on SSU rRNA gene sequences revealed that all Coleps species were grouped together, except for Coleps amphacanthus, which was grouped into a clade of the genus Levicoleps.
基金Project(2013CB73300)supported by the National Basic Research Program of ChinaProjects(51531005,51434008,51571174)supported by the National Natural Science Foundation of China
文摘The deformation behavior and microstructure of the Zr50Ti50 alloy in β phase field were investigated by isothermal compression tests at temperatures ranging from 700 to 850 °C and strain rates ranging from 0.001 to 1 s?1. The flow curves exhibited typical flow softening. The initial discontinuous yielding behavior was observed at higher strain rates, which was not found in other traditional Zr alloys. The apparent deformation activation energy was calculated to be 103 kJ/mol and constitutive equationdescribing the flow stress as a function of the strain rate and deformation temperature was proposed. The analysis indicated that the hot deformation mechanism was mainly dominated by dynamic recovery. However, dynamic recrystallization was delayed by dynamic recovery. Thereafter, the processing map was calculated to evaluate the efficiency of the forging process at the temperatures and strain rates investigated and to optimize processing parameters of hot deformation. The optimum processing parameters were found to be 830?850 °C and 0.56?1 s?1 for hot the deformation of Zr50Ti50 alloy in the β phase region.
基金supported by the National Natural Science Foundation of China(Grant Nos.:51434008,51671166,51471143)。
文摘Many amorphous alloys have been developed to date,but the low plasticity has limited their application.To achieve an amorphous alloy with high plasticity,a series of(Ti_(40)Zr_(25)Cu_(9)Ni_(8) Be_(18))_(100-x)TM_(x)(x=0,1,2,3,4 at.%,TM=Nb,Y)alloys were designed to study the influence of Nb and Y addition on the plasticity.The amorphous samples were prepared using the vacuum melting and copper mold casting process.The microstructures,glass forming ability and mechanical properties of the alloys were investigated by X-ray diffractometry(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),depth-sensitive nanoindentation,and uniaxial compressive test.The plasticity of different bulk amorphous alloys was investigated by measuring the plastic deformation energy(PDE)during loading.The relationship between the PDE value and plasticity in bulk amorphous alloys was explored.Results show that Nb addition decreases the PDE value and promotes the generation of multiple shear bands,which significantly increases the fracture strength and plasticity,while the addition of Y element reduces the fracture strength and plastic strain of the alloy.
基金Supported by the Postdoctoral Science Foundation of Hebei Province under Grant No B2017003008the National Natural Science Foundation of China under Grant Nos 51531005,51671166,51571174 and 51604241the Natural Science Foundation of Hebei Province under Grant No E2016203395
文摘Thermal expansion is a common phenomenon in both metals and alloys, which is important for metallic material applications in modern industry, especially in nuclear and aerospace industries. A lower thermal expansion coefficient may cause lower thermal stress and higher accuracy. A new Zr-based alloy is developed and presented.The XRD diffraction results demonstrate that only a close-packed hexagonal phase（α or α＇ phase） exists in the microstructure. The thermal expansion and mechanical properties are studied. According to the experimental results, the new Zr-based alloy presents a low thermal expansion coefficient and good mechanical properties.Also,its thermal expansion coefficient is stable through solution treatment.
基金supported by the National Natural Science Foundation of China (Nos. 52071278, 51827801)the National Key Research and Development Program of China (No. 2018YFA0703603)。
基金the National Natural Science Foundation of China(Nos.52071278,51827801)the National Key Research and Development Program of China(No.2018YFA0703603)the Hebei Normal University of Science&Technology,China(No.2021YB012).
文摘An outer ring of 29320 self-aliging roller bearing was used in an experimental study on the casting of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5) amorphous alloy.Numerical simulations of mold filling and solidification processes were carried out to determine the velocity fields and temperature fields of the alloy melt during mold filling process as well as the temperature fields and temperature gradient fields in the course of the solidification.According to the results,a cast with a complete shape can be obtained at 1200℃under the condition that the cooling rate is greater than the critical cooling rate.The ring-shaped part with a thickness of 25 mm,an equivalent diameter of 22 mm,and a mass of 1.32 kg was prepared by gravity casting in a copper mold.X-ray diffraction and differential scanning calorimetry data revealed that the produced cast had the amorphous structure.
基金financially supported by the National Basic Research Program of China(No.2013CB733000)the National High Technology Research and Development Program of China(No.2013AA031304)
文摘An Al-Mg-Si-Cu-Fe alloy was solid-solution treated at 560℃ for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temperatures. The microstructure and mechanical properties of the rolled alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and tensile testing. For the water-quenched alloys, the peak tensile strength and elongation occurred at a rolling temperature of 180℃. For the furnace-cooled alloys, the tensile strength decreased initially, until the rolling temperature of 420℃, and then increased;the elongation increased consistently with increasing rolling temperature. The effects of grain boundary hardening and dislocation hardening on the mechanical properties of these rolled alloys decreased with increases in rolling temperature. The mechanical properties of the 180℃ rolling water-quenched alloy were also improved by the presence ofβ″phase. Above 420℃, the effect of solid-solution hardening on the mechanical properties of the rolled alloys increased with increases in rolling temperature.
基金Projects(51671166,51434008)supported by the National Natural Science Foundation of ChinaProject(2013CB733000)supported by the National Basic Research Program of China
文摘ZrO2 dispersion-strengthened Q345 steel with different ZrO2 contents（0%, 0.5% and 1.2%, mass fraction） was fabricated through combining middle frequency induction furnace melting and cored-wire injection technologies. The microstructure and fracture surface morphology of ZrO2 dispersion-strengthened Q345 steel in casting, normalizing and quenching states were observed using optical microscopy, scanning electron microscopy and transmission electron microscopy. Also, strengthening and fracture mechanisms of the alloys were analyzed. Results showed that the dispersed ZrO2 particles added into Q345 matrix significantly enhanced its strength, and the main strengthening mechanism was the formation of dislocation cells and pinning effect caused by the addition of ZrO2 particles. Apart from that, the hard martensite phase, grain refinement and high ZrO2 particles content also played important roles in strengthening effect. Furthermore, the nanoindentation was also performed to further reveal the strengthening effect and mechanism of dispersed ZrO2 particles in Q345 steel. Results showed that the hardness of ZrO2 dispersion-strengthened Q345 steel increased with the increase of ZrO2 content.
基金National Natural Science Foundation of China(Nos.51671166,51827801 and 51434008)Youth Fund of the Education Department in Hebei Province (QN2018305).
文摘Understanding the flow characteristics of amorphous metal melts is important for casting and molding processes.Fluidity of Zr-based amorphous metal melts was determined by using a self-designed apparatus.Phase analysis demonstrated that the fluidity test samples were fuUy amorphous structure.The onset crystallization temperature significantly moved toward high temperature with the increases of casting temperature,which improved the glass-forming ability and thermal stability of Zr-based amorphous metal.Fluidity test results demonstrated that the fluidity length increased monotonically with the increases of temperature,pressure,and runner diameter.By identifying the types and quantities of the defect in castings,it could conclude that smooth filling processes occurred under appropriate conditions.Experimental results indicated that the flow behavior of the Zr-based amorphous metal melts strongly depended on the casting temperature and equivalent thickness.Constitutive equation based on Newton's law of heat exchange and Rayleigh rule was established to'evaluate the fluidity of Zr-based amorphous metal melts.Theoretical calculations and experimental tests were basically coincided with each other.The determined optimal casting temperatures and equivalent thicknesses were adopted to successfully fabricate a series of fully shaped castings through gravity casting.
基金financially supported by the National Natural Science Foundation of China (Nos.51101003 and 51471012)
文摘A significant refinement of the microstructure of structural NiTi alloy was achieved through a combination of Al addition and fabrication by suction casting.This is attributed to the change from a layer-by-layer to volume solidification mode with Al content increasing,which causes a change in grain shape from columnar to equiaxed.Furthermore,when compared with conventional casting,suction casting optimizes the microstructure of the alloy by refining the grain size and ensuring a homogeneous distribution of Ti2 Ni and Ni_(2)TiAl phases.The high cooling rate of suction casting also delays the formation ofβ'-Ni_(2)TiAl phase.Finally,this fine microstructure and uniform distribution of intermetallic phases result in the ultimate compressive strength of up to 2463.7 MPa,representing an improvement of 370 MPa over conventionally cast NiTi-Al alloy.
