The magnetic and structural properties in Co/Cu/Co sandwiches with Ni and Cr buffer layers were investigated. It was found that the coercivity in Ni layer buffered samples decreases with increasing Ni layer thickness,...The magnetic and structural properties in Co/Cu/Co sandwiches with Ni and Cr buffer layers were investigated. It was found that the coercivity in Ni layer buffered samples decreases with increasing Ni layer thickness, while that in Cr layer buffered ones increases with increasing Cr layer thickness, leading to a large difference in field sensitivity of their giant magnetoresistance (GMR) properties. X-ray diffraction and high resolution transmission electron microscope images exhibited that there is a strong fcc (111) texture in the samples with Ni buffer layer. But there are only randomly oriented potycrystalline grains in Cr buffered sandwiches. According to atomic force microscope topography, the surface roughness of Cr buffered sandwiches is smaller than that of Ni buffered ones. It is demonstrated that buffer layer influences both magnetic and structural properties in Co/Cu/Co sandwiches as well as their GMR characteristics.展开更多
The liquid state undercoolability and crystal growth kinetics of ternary Ni-5%Cu-5%Sn and Ni-10%Cu-10%Sn alloys are investigated by the glass fluxing method. In these two alloys, experimental maximum undercoolings of ...The liquid state undercoolability and crystal growth kinetics of ternary Ni-5%Cu-5%Sn and Ni-10%Cu-10%Sn alloys are investigated by the glass fluxing method. In these two alloys, experimental maximum undercoolings of 304 K （0.18TL ） and 286K （0.17TL ） are achieved and the dendritic growth velocities attain 39.8 and 25.1 m/s, respectively. The transition of morphology from coarse dendrite into equiaxed structure occurs and the grain size of the a （Ni） phase decreases remarkably when the undercooling increases. Both the lattice constant and microhardness increase obviously with the enhancement of undercooling. The enrichment of Cu and Sn solute contents reduces the dendritic growth velocity, while enhances the lattice constant and microhardness of a （Ni） phase.展开更多
Schiff base ligand （HL） derived from 4-hexylaniline with isatin （1H-indole-2,3-dione） and its complexes with Cu（Ⅱ）, Ni（Ⅱ） were prepared and characterized by analytical, spectroscopic （IR, UV-Vis, Mass） tec...Schiff base ligand （HL） derived from 4-hexylaniline with isatin （1H-indole-2,3-dione） and its complexes with Cu（Ⅱ）, Ni（Ⅱ） were prepared and characterized by analytical, spectroscopic （IR, UV-Vis, Mass） techniques, electrical conductivity, magnetic and thermal measurements. The crystal and molecular structure of [Cu（HL）2Cl2] was determined by a single-crystal X-ray diffraction study. The molecular structure of the title compound has an inversion center on the Cu atom.展开更多
The Voisey's Bay Ni-Cu-Co sulfide deposit is hosted in a 1.34 Ga mafic intrusion that is part of the Nain Plutonic Suite in Labrador, Canada.The Ni-Cu-Co sulfide mineralization is associated with magmatic breccias...The Voisey's Bay Ni-Cu-Co sulfide deposit is hosted in a 1.34 Ga mafic intrusion that is part of the Nain Plutonic Suite in Labrador, Canada.The Ni-Cu-Co sulfide mineralization is associated with magmatic breccias that are typically contained in weakly mineralized olivine gabbros, troctolites and ferrogabbros, but also occur as veins in adjacent paragneiss.The mineralization is associated with a dyke-like body which is termed the feeder dyke.This dyke connects the shallow differentiated Eastern Deeps chamber in the east to a deeper intrusion in the west termed the Western Deeps Intrusion.Where the conduit is connected to the Eastern Deeps Intrusion, the Eastern Deeps Deposit is developed at the entry line of the dyke along the steep north wall of the Eastern Deeps Intrusion.The Eastern Deeps Deposit is surrounded by a halo of moderately to weakly mineralized Variable-Textured Troctolite (VTT) that reaches a maximum thickness above the ENE-WSW axis of the Eastern Deeps Deposit. At depth to the west, the conduit is adjacent to the south side of the Western Deeps Intrusion, where the dyke and intrusion contain disseminated magmatic sulfide mineralization.The Reid Brook Zone plunges to the east within the dyke, and both the dyke and adjacent paragneiss are mineralized.The Ovoid Deposit comprises a bowl-shaped body of massive sulfide where the dyke widens near to the present-day surface.It is not clear whether this deposit was developed as a widened-zone within the conduit or at the entry point into a chamber that is now lost to erosion. The massive sulfides and breccia sulfides of the Eastern Deeps are petrologically and chemically different when compared to the disseminated sulfides in the VTT; there is a marked break in Ni tenor (Ni content in 100% sulfide, abbreviated to [Ni]100) and Ni/Co of sulfide between the two.The boundary of the sulfide types is often marked by strong sub-horizontal alignment of heavily digested and metamorphosed paragneiss fragments, development of barren olivine gabbro, and by a change from typically massive sulfides and breccias sulfides into more typical variable-textured troctolites with heavy to weak disseminated sulfide.Sulfides hosted in the feeder dyke tend to have low metal tenors ([Ni]100=2.5%-3.5%); sulfides in Eastern Deeps massive and breccia ores have intermediate Ni tenors ([Ni]100=3.5%-4%) and disseminated sulfides in overlying rocks have high Ni tenors ([Ni] 100=4%-8%) . Conduit-hosted mineralization and mineral zones in the paragneiss adjacent to the Reid Brook Deposit tend to have lower Ni tenor than the Ovoid and Eastern Deeps Deposits.The tenor of mineral hosted in the country rock gneisses tends to be the same as that developed in the conduit ; the injection of the sulfide into the country rocks likely occurred before formation of monosulfide solid solution.The Ovoid Deposit is characterized by coarse-grained loop-textured ores consisting of 10cm-2msized pyrrhotite crystals separated by chalcopyrite and pentlandite.A small lens of massive cubanite surrounded by more magnetite-rich sulfide assemblages represents what appears to be the product of in-situ sulfide fractionation. Detailed exploration in the area between the Reid Brook Zone and the Eastern Deeps has shown that these intrusions and ore deposits are connected by a branched dyke and chamber system in a major westeast fault zone.The Eastern Deeps chamber may be controlled by graben-like fault structures , and the marginal structures appear to have controlled dykes which connect the chambers at different levels in the crust.The geological relationships in the intrusion are consistent with emplacement of the silicate and sulfide laden magma from a deeper sub-chamber (possibly a deep eastward extension of the Western Deeps Intrusion where S-saturation was initially achieved) .The silicate and sulfide magmas were likely emplaced through this conduit into the Eastern Deeps intrusion as a number of different fragment laden pulses of sulfide-silicate melt that evolved with different R factors and in response to some variation in the degree of evolution of the parental magma.S isotope and S/Se data coupled with geological evidence point to a crustal source for the sulfur , and the site of equilibration of mafic magma and crustal S is placed at depth in a sulfidic Tasiuyak Gneiss. The structural control on emplacement of small intrusions with transported sulfide is a feature found in different nickel sulfide deposits around the world.Champagne glass-shaped openings in sub-vertical chonoliths are a common morphology for this deposit type (e.g.the Jinchuan , Huangshan , Huangshandong , Jingbulake , Limahe , Hong Qi Ling deposits in China , the Eagle deposits in the United States , and the Double Eagle deposit in Canada) .Some of the structures of the Midcontinent Rift of North America also host Ni-Cu-(PGE) deposits of this type (e.g.the Current Lake Complex in the Quetico Fault Zone in Ontario , Canada and the Tamarac mineralisation in the Great Lakes Structural Zone of the United States) .Other major nickel deposits associated with flat structures adjacent to major mantle-penetrating structures include the Noril'sk , Noril'sk II , Kharaelakh , NW Talnakh , and NE Talnakh Intrusions of the Noril'sk Region of Russia , the Kalatongke deposit in NW China , and Babel-Nebo in Western Australia.These deposits are all formed in mantle-penetrating structural conduits that link into the roots of large igneous provinces near the edges of old cratons.展开更多
A nickel-based coating was deposited on the pure Al substrate by immersion plating,and the Al/Cu bimetals were prepared by diffusion bonding in the temperature range of 450-550 ℃.The interce microstructure and fractu...A nickel-based coating was deposited on the pure Al substrate by immersion plating,and the Al/Cu bimetals were prepared by diffusion bonding in the temperature range of 450-550 ℃.The interce microstructure and fracture surface of Al/Cu joints were studied by scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The mechanical properties of the Al/Cu bimetals were measured by tensile shear and microhardness tests.The results show that the Ni interiayer can effectively eliminate the formation of Al-Cu intermetallic compounds.The Al/Ni interface consists of the Al3Ni and Al3Ni2 phases,while it is Ni-Cu solid solution at the Ni/Cu interce.The tensile shear strength of the joints is improved by the addition of Ni interiayer.The joint with Ni interiayer annealed at 500 ℃ exhibits a maximum value of tensile shear strength of 34.7 MPa.展开更多
The superelastic behaviors of different isothermal treated Cu-13.SAl-4.ONi (mass fraction) single crystals were studied by applying tensile stress along <001> of the d phase. The different isothermal specimens h...The superelastic behaviors of different isothermal treated Cu-13.SAl-4.ONi (mass fraction) single crystals were studied by applying tensile stress along <001> of the d phase. The different isothermal specimens have different superelastic behavior due to the change of the ratio of stress-induced r1 and β1. The superelasticity of r1 phase tends to that of g; phase with cycling. Typical stabilization of stress-induced martensite above Ap results in residual deformation. Due to the reverse transformation of 7I, there is a deviation of pseudo-yield stress from linear relation with temperature at relatively low stress.展开更多
Two quinary high-entropy alloys （HEAs） with equiatomic concentrations formed by doping either Cu or A1 elements into the quaternary NiFeCoCr alloy are produced by arc melting and spray casting techniques. Their entr...Two quinary high-entropy alloys （HEAs） with equiatomic concentrations formed by doping either Cu or A1 elements into the quaternary NiFeCoCr alloy are produced by arc melting and spray casting techniques. Their entropy of fusion, thermal expansion coefficient and thermal diffusivity are experimentally investigated with differential scanning cMorimetry, dilatometry and laser flash methods. The NiFeCoCrCu HEAs contain a face- centered cubic high-entropy phase plus a minor interdendritic （Cu） phase and display a lower entropy of fasion and the Vickers hardness. The NiFeCoCrAl HEAs consist of two body-centered cubie high-entropy phases with coarse dendritic structures and show higher entropy of fusion and the Vickers hardness. Both the thermal expansion coefficient and the thermal diffusivity of the former Cu-doped alloy are signitieantly larger than those of the latter At-doped M1oy. Although the temperature dependence of thermal diffusivity is similar for both HEAs, it is peculiar that the thermal expansion curve of the NiFeCoCrAl alloy exhibits an inflexion at temperatures of 860-912 K.展开更多
The present investigation evaluated the effectiveness of Chlorella cells in concentrating Cu and Ni in their cells and thereby removing the two metals from solution. The removal efficiency of the two metals by free an...The present investigation evaluated the effectiveness of Chlorella cells in concentrating Cu and Ni in their cells and thereby removing the two metals from solution. The removal efficiency of the two metals by free and immobilized algal cells were further studied. (1) Four types of Chlorella cells, namely Chlorella pyrenoidosa (26) (from Carolina Biological Supplies Company), Chlorella HKBC-1 and-2 (isolated from a polluted stream receiving wastewater from several electroplating factories) and Chlorella HKBC-3 (from a clean water pond) were subjected to different concentrations of Cu and Ni accordingly. It was revealed that Chlorella HKBC-1 was the most tolerant species toCu and Ni as reflected by their highest values of 48 h and 96 h 'Highest no effect concentrations' (The highest concentration of the tested substance that does not inhibit the growth rate of the alga: Cu 2 and Ni 10 mg/1 at 48 h, Cu 2 and Ni 5 at 96 h). This was followed by C. pyrenoidosa (26) and then C. HKBC-2 while C. HKBC-3 had the lowest tolerance to the two metals (Cu 0.5 and Ni 2 at 48 h; Cu 0.5 and Ni 1 mg/1 at 96 h). (2) It was further revealed that C. HKBC-1 had higher concentration factors and removal efficiencies of Ni (734-963 mg/1, 16.3-18.7%) and C. HKBC-2 had higher concentration factors and removal efficiencies of Cu (2316-2839 mg/1, 53.7-66%) when exposed to lower concentrations of Cu (0.5,1 and 2 mg/1) and Ni (5, 10 and 13 mg/1). (3) By treating the free and immobilized algal cells (algal cells entrapped in alginate beads) with different concentrations of Cu and Ni, it was observed that free cells had higher concentration factors and removal efficiencies when compared with immobilized cells (free cells: Cu 1577-3056 mg/1, 24.2-71.4%; Ni 355-849 mg/1, 4.8-18.7%; immobilized cells: Cu 453-935 mg/1, 13.9-53.2%; Ni 244-486 mg/1, 3.2-11.9%).展开更多
纳米材料因其自身独特性能而备受关注,从而引发了人们对其进行一系列的研究。采用机械合金化法(MA)和粉末冶金法(PM)制备了纳米尺寸和常规尺寸粉末,通过控制温度和压力等因素,利用真空热压烧结炉将两种不同尺寸的Cu-20Co-20Cr-20Ni粉末...纳米材料因其自身独特性能而备受关注,从而引发了人们对其进行一系列的研究。采用机械合金化法(MA)和粉末冶金法(PM)制备了纳米尺寸和常规尺寸粉末,通过控制温度和压力等因素,利用真空热压烧结炉将两种不同尺寸的Cu-20Co-20Cr-20Ni粉末热压成块体合金,并利用电化学测试技术研究了它们在0.5mol·L^(-1)中性Na Cl溶液中的腐蚀行为以及纳米化对其腐蚀行为的影响。结果表明:当Cu-20Co-20Cr-20Ni合金处于0.5mol·L^(-1) Na Cl腐蚀溶液中时,纳米尺寸Cu-20Co-20Cr-20Ni合金较相应的常规尺寸合金自腐蚀电位发生正移,电荷传递电阻变大,腐蚀电流密度减小。可见,晶粒细化导致Cu-20Co-20Cr-20Ni合金的耐腐蚀性能增强。展开更多
The homogeneous plastic flow of fully amorphous and partially crystallized Zr(41.2)Ti(13.8)Cu(12.5)Ni(10)Be(22.5) bulk metallic glass (Vitl) has been investigated by compression tests at high temperatures in supercool...The homogeneous plastic flow of fully amorphous and partially crystallized Zr(41.2)Ti(13.8)Cu(12.5)Ni(10)Be(22.5) bulk metallic glass (Vitl) has been investigated by compression tests at high temperatures in supercooled liquid region. Experimental results show that at sufficiently low strain rates, the supercooled liquid of the fully amorphous alloy reveals Newtonian flow with a linear relationship between the flow stress and strain rate. As the strain rate is increased, a transition from linear Newtonian to nonlinear flow is detected, which can be explained by the transition state theory. Over the entire strain rate interval investigated, however, only nonlinear flow is present in the partially crystallized alloy, and the flow stress for each strain rate is much higher. It is found that the strain rate-stress relationship for the partially crystaltized alloy at the given temperature of 646 K also obeys the sinh law derived from the transition state theory, similar to that of the initial homogeneous amorphous alloy. Thus, it is proposed that the flow behavior of the nanocrystalline/amorphous composite at 646 K is mainly controlled by the viscous flow of the remaining supercooled liquid.展开更多
The effects of deep cryogenic treatment on mechanical behavior of a Cu-Cr-Zr alloy for electrodes of spot welding were investigated employing Brinell-hardness testing unit, abrasion examination machine, electronic alm...The effects of deep cryogenic treatment on mechanical behavior of a Cu-Cr-Zr alloy for electrodes of spot welding were investigated employing Brinell-hardness testing unit, abrasion examination machine, electronic almighty testing machine and X-ray stress analyzer. Tensile fracture surfaces of the alloy were characterized by scanning electronic microscope （SEM） with energy dispersive X-ray spectroscopy （EDS）. The results showed that, after deep cryogenic treatment, σb and σ0.2 increased 23 MPa and 21 MPa respectively, the wear rate of the alloy exhibited the trend of decrease with the decreasing temperature and increasing time of deep cryogenic treatment, and the surface residual stress of the alloy was partially eliminated by deep cryogenic treatment.展开更多
文摘The magnetic and structural properties in Co/Cu/Co sandwiches with Ni and Cr buffer layers were investigated. It was found that the coercivity in Ni layer buffered samples decreases with increasing Ni layer thickness, while that in Cr layer buffered ones increases with increasing Cr layer thickness, leading to a large difference in field sensitivity of their giant magnetoresistance (GMR) properties. X-ray diffraction and high resolution transmission electron microscope images exhibited that there is a strong fcc (111) texture in the samples with Ni buffer layer. But there are only randomly oriented potycrystalline grains in Cr buffered sandwiches. According to atomic force microscope topography, the surface roughness of Cr buffered sandwiches is smaller than that of Ni buffered ones. It is demonstrated that buffer layer influences both magnetic and structural properties in Co/Cu/Co sandwiches as well as their GMR characteristics.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51327901 and 51301138the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20126102120064+1 种基金the Aviation Science Foundation of China under Grant No 2014ZF53069the Fundamental Research Funds for the Central Universities under Grant No3102014KYJD044
文摘The liquid state undercoolability and crystal growth kinetics of ternary Ni-5%Cu-5%Sn and Ni-10%Cu-10%Sn alloys are investigated by the glass fluxing method. In these two alloys, experimental maximum undercoolings of 304 K （0.18TL ） and 286K （0.17TL ） are achieved and the dendritic growth velocities attain 39.8 and 25.1 m/s, respectively. The transition of morphology from coarse dendrite into equiaxed structure occurs and the grain size of the a （Ni） phase decreases remarkably when the undercooling increases. Both the lattice constant and microhardness increase obviously with the enhancement of undercooling. The enrichment of Cu and Sn solute contents reduces the dendritic growth velocity, while enhances the lattice constant and microhardness of a （Ni） phase.
文摘Schiff base ligand （HL） derived from 4-hexylaniline with isatin （1H-indole-2,3-dione） and its complexes with Cu（Ⅱ）, Ni（Ⅱ） were prepared and characterized by analytical, spectroscopic （IR, UV-Vis, Mass） techniques, electrical conductivity, magnetic and thermal measurements. The crystal and molecular structure of [Cu（HL）2Cl2] was determined by a single-crystal X-ray diffraction study. The molecular structure of the title compound has an inversion center on the Cu atom.
文摘The Voisey's Bay Ni-Cu-Co sulfide deposit is hosted in a 1.34 Ga mafic intrusion that is part of the Nain Plutonic Suite in Labrador, Canada.The Ni-Cu-Co sulfide mineralization is associated with magmatic breccias that are typically contained in weakly mineralized olivine gabbros, troctolites and ferrogabbros, but also occur as veins in adjacent paragneiss.The mineralization is associated with a dyke-like body which is termed the feeder dyke.This dyke connects the shallow differentiated Eastern Deeps chamber in the east to a deeper intrusion in the west termed the Western Deeps Intrusion.Where the conduit is connected to the Eastern Deeps Intrusion, the Eastern Deeps Deposit is developed at the entry line of the dyke along the steep north wall of the Eastern Deeps Intrusion.The Eastern Deeps Deposit is surrounded by a halo of moderately to weakly mineralized Variable-Textured Troctolite (VTT) that reaches a maximum thickness above the ENE-WSW axis of the Eastern Deeps Deposit. At depth to the west, the conduit is adjacent to the south side of the Western Deeps Intrusion, where the dyke and intrusion contain disseminated magmatic sulfide mineralization.The Reid Brook Zone plunges to the east within the dyke, and both the dyke and adjacent paragneiss are mineralized.The Ovoid Deposit comprises a bowl-shaped body of massive sulfide where the dyke widens near to the present-day surface.It is not clear whether this deposit was developed as a widened-zone within the conduit or at the entry point into a chamber that is now lost to erosion. The massive sulfides and breccia sulfides of the Eastern Deeps are petrologically and chemically different when compared to the disseminated sulfides in the VTT; there is a marked break in Ni tenor (Ni content in 100% sulfide, abbreviated to [Ni]100) and Ni/Co of sulfide between the two.The boundary of the sulfide types is often marked by strong sub-horizontal alignment of heavily digested and metamorphosed paragneiss fragments, development of barren olivine gabbro, and by a change from typically massive sulfides and breccias sulfides into more typical variable-textured troctolites with heavy to weak disseminated sulfide.Sulfides hosted in the feeder dyke tend to have low metal tenors ([Ni]100=2.5%-3.5%); sulfides in Eastern Deeps massive and breccia ores have intermediate Ni tenors ([Ni]100=3.5%-4%) and disseminated sulfides in overlying rocks have high Ni tenors ([Ni] 100=4%-8%) . Conduit-hosted mineralization and mineral zones in the paragneiss adjacent to the Reid Brook Deposit tend to have lower Ni tenor than the Ovoid and Eastern Deeps Deposits.The tenor of mineral hosted in the country rock gneisses tends to be the same as that developed in the conduit ; the injection of the sulfide into the country rocks likely occurred before formation of monosulfide solid solution.The Ovoid Deposit is characterized by coarse-grained loop-textured ores consisting of 10cm-2msized pyrrhotite crystals separated by chalcopyrite and pentlandite.A small lens of massive cubanite surrounded by more magnetite-rich sulfide assemblages represents what appears to be the product of in-situ sulfide fractionation. Detailed exploration in the area between the Reid Brook Zone and the Eastern Deeps has shown that these intrusions and ore deposits are connected by a branched dyke and chamber system in a major westeast fault zone.The Eastern Deeps chamber may be controlled by graben-like fault structures , and the marginal structures appear to have controlled dykes which connect the chambers at different levels in the crust.The geological relationships in the intrusion are consistent with emplacement of the silicate and sulfide laden magma from a deeper sub-chamber (possibly a deep eastward extension of the Western Deeps Intrusion where S-saturation was initially achieved) .The silicate and sulfide magmas were likely emplaced through this conduit into the Eastern Deeps intrusion as a number of different fragment laden pulses of sulfide-silicate melt that evolved with different R factors and in response to some variation in the degree of evolution of the parental magma.S isotope and S/Se data coupled with geological evidence point to a crustal source for the sulfur , and the site of equilibration of mafic magma and crustal S is placed at depth in a sulfidic Tasiuyak Gneiss. The structural control on emplacement of small intrusions with transported sulfide is a feature found in different nickel sulfide deposits around the world.Champagne glass-shaped openings in sub-vertical chonoliths are a common morphology for this deposit type (e.g.the Jinchuan , Huangshan , Huangshandong , Jingbulake , Limahe , Hong Qi Ling deposits in China , the Eagle deposits in the United States , and the Double Eagle deposit in Canada) .Some of the structures of the Midcontinent Rift of North America also host Ni-Cu-(PGE) deposits of this type (e.g.the Current Lake Complex in the Quetico Fault Zone in Ontario , Canada and the Tamarac mineralisation in the Great Lakes Structural Zone of the United States) .Other major nickel deposits associated with flat structures adjacent to major mantle-penetrating structures include the Noril'sk , Noril'sk II , Kharaelakh , NW Talnakh , and NE Talnakh Intrusions of the Noril'sk Region of Russia , the Kalatongke deposit in NW China , and Babel-Nebo in Western Australia.These deposits are all formed in mantle-penetrating structural conduits that link into the roots of large igneous provinces near the edges of old cratons.
基金Projects (51274054,51375070,51271042) supported by the National Natural Science Foundation of ChinaProjects (2013M530913) supported by the China Postdoctoral Science Foundation
文摘A nickel-based coating was deposited on the pure Al substrate by immersion plating,and the Al/Cu bimetals were prepared by diffusion bonding in the temperature range of 450-550 ℃.The interce microstructure and fracture surface of Al/Cu joints were studied by scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The mechanical properties of the Al/Cu bimetals were measured by tensile shear and microhardness tests.The results show that the Ni interiayer can effectively eliminate the formation of Al-Cu intermetallic compounds.The Al/Ni interface consists of the Al3Ni and Al3Ni2 phases,while it is Ni-Cu solid solution at the Ni/Cu interce.The tensile shear strength of the joints is improved by the addition of Ni interiayer.The joint with Ni interiayer annealed at 500 ℃ exhibits a maximum value of tensile shear strength of 34.7 MPa.
文摘The superelastic behaviors of different isothermal treated Cu-13.SAl-4.ONi (mass fraction) single crystals were studied by applying tensile stress along <001> of the d phase. The different isothermal specimens have different superelastic behavior due to the change of the ratio of stress-induced r1 and β1. The superelasticity of r1 phase tends to that of g; phase with cycling. Typical stabilization of stress-induced martensite above Ap results in residual deformation. Due to the reverse transformation of 7I, there is a deviation of pseudo-yield stress from linear relation with temperature at relatively low stress.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51571163,51371150,51271150 and 51327901
文摘Two quinary high-entropy alloys （HEAs） with equiatomic concentrations formed by doping either Cu or A1 elements into the quaternary NiFeCoCr alloy are produced by arc melting and spray casting techniques. Their entropy of fusion, thermal expansion coefficient and thermal diffusivity are experimentally investigated with differential scanning cMorimetry, dilatometry and laser flash methods. The NiFeCoCrCu HEAs contain a face- centered cubic high-entropy phase plus a minor interdendritic （Cu） phase and display a lower entropy of fasion and the Vickers hardness. The NiFeCoCrAl HEAs consist of two body-centered cubie high-entropy phases with coarse dendritic structures and show higher entropy of fusion and the Vickers hardness. Both the thermal expansion coefficient and the thermal diffusivity of the former Cu-doped alloy are signitieantly larger than those of the latter At-doped M1oy. Although the temperature dependence of thermal diffusivity is similar for both HEAs, it is peculiar that the thermal expansion curve of the NiFeCoCrAl alloy exhibits an inflexion at temperatures of 860-912 K.
文摘The present investigation evaluated the effectiveness of Chlorella cells in concentrating Cu and Ni in their cells and thereby removing the two metals from solution. The removal efficiency of the two metals by free and immobilized algal cells were further studied. (1) Four types of Chlorella cells, namely Chlorella pyrenoidosa (26) (from Carolina Biological Supplies Company), Chlorella HKBC-1 and-2 (isolated from a polluted stream receiving wastewater from several electroplating factories) and Chlorella HKBC-3 (from a clean water pond) were subjected to different concentrations of Cu and Ni accordingly. It was revealed that Chlorella HKBC-1 was the most tolerant species toCu and Ni as reflected by their highest values of 48 h and 96 h 'Highest no effect concentrations' (The highest concentration of the tested substance that does not inhibit the growth rate of the alga: Cu 2 and Ni 10 mg/1 at 48 h, Cu 2 and Ni 5 at 96 h). This was followed by C. pyrenoidosa (26) and then C. HKBC-2 while C. HKBC-3 had the lowest tolerance to the two metals (Cu 0.5 and Ni 2 at 48 h; Cu 0.5 and Ni 1 mg/1 at 96 h). (2) It was further revealed that C. HKBC-1 had higher concentration factors and removal efficiencies of Ni (734-963 mg/1, 16.3-18.7%) and C. HKBC-2 had higher concentration factors and removal efficiencies of Cu (2316-2839 mg/1, 53.7-66%) when exposed to lower concentrations of Cu (0.5,1 and 2 mg/1) and Ni (5, 10 and 13 mg/1). (3) By treating the free and immobilized algal cells (algal cells entrapped in alginate beads) with different concentrations of Cu and Ni, it was observed that free cells had higher concentration factors and removal efficiencies when compared with immobilized cells (free cells: Cu 1577-3056 mg/1, 24.2-71.4%; Ni 355-849 mg/1, 4.8-18.7%; immobilized cells: Cu 453-935 mg/1, 13.9-53.2%; Ni 244-486 mg/1, 3.2-11.9%).
文摘纳米材料因其自身独特性能而备受关注,从而引发了人们对其进行一系列的研究。采用机械合金化法(MA)和粉末冶金法(PM)制备了纳米尺寸和常规尺寸粉末,通过控制温度和压力等因素,利用真空热压烧结炉将两种不同尺寸的Cu-20Co-20Cr-20Ni粉末热压成块体合金,并利用电化学测试技术研究了它们在0.5mol·L^(-1)中性Na Cl溶液中的腐蚀行为以及纳米化对其腐蚀行为的影响。结果表明:当Cu-20Co-20Cr-20Ni合金处于0.5mol·L^(-1) Na Cl腐蚀溶液中时,纳米尺寸Cu-20Co-20Cr-20Ni合金较相应的常规尺寸合金自腐蚀电位发生正移,电荷传递电阻变大,腐蚀电流密度减小。可见,晶粒细化导致Cu-20Co-20Cr-20Ni合金的耐腐蚀性能增强。
文摘The homogeneous plastic flow of fully amorphous and partially crystallized Zr(41.2)Ti(13.8)Cu(12.5)Ni(10)Be(22.5) bulk metallic glass (Vitl) has been investigated by compression tests at high temperatures in supercooled liquid region. Experimental results show that at sufficiently low strain rates, the supercooled liquid of the fully amorphous alloy reveals Newtonian flow with a linear relationship between the flow stress and strain rate. As the strain rate is increased, a transition from linear Newtonian to nonlinear flow is detected, which can be explained by the transition state theory. Over the entire strain rate interval investigated, however, only nonlinear flow is present in the partially crystallized alloy, and the flow stress for each strain rate is much higher. It is found that the strain rate-stress relationship for the partially crystaltized alloy at the given temperature of 646 K also obeys the sinh law derived from the transition state theory, similar to that of the initial homogeneous amorphous alloy. Thus, it is proposed that the flow behavior of the nanocrystalline/amorphous composite at 646 K is mainly controlled by the viscous flow of the remaining supercooled liquid.
基金[This work was financially supported by the National Natural Science Foundation of China (No. 50175080) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (SRFDP: No. 20030056003).]
文摘The effects of deep cryogenic treatment on mechanical behavior of a Cu-Cr-Zr alloy for electrodes of spot welding were investigated employing Brinell-hardness testing unit, abrasion examination machine, electronic almighty testing machine and X-ray stress analyzer. Tensile fracture surfaces of the alloy were characterized by scanning electronic microscope （SEM） with energy dispersive X-ray spectroscopy （EDS）. The results showed that, after deep cryogenic treatment, σb and σ0.2 increased 23 MPa and 21 MPa respectively, the wear rate of the alloy exhibited the trend of decrease with the decreasing temperature and increasing time of deep cryogenic treatment, and the surface residual stress of the alloy was partially eliminated by deep cryogenic treatment.
