The microstructure of as-cast Zr60Al15Ni25 bulk metallic glass was investigated by high-resolution transmission electron microscopy. It is found that there exist numerous short-range order regions (SRORs) in the met...The microstructure of as-cast Zr60Al15Ni25 bulk metallic glass was investigated by high-resolution transmission electron microscopy. It is found that there exist numerous short-range order regions (SRORs) in the metallic glass though it is identified to be amorphous by X-ray diffraction method. Furthermore, the amorphous degree shows a close correlation with the microstructure of corresponding mother ingot. The crystallization kinetics was investigated by differential scanning calorimetry under isochronal and isothermal conditions. The results show that the crystallization is triggered by the growth of the pre-existing SRORs and the growth is three-dimension diffusion-controlled. The amorphous degree of Zr60Al15Ni25 bulk metallic glass considerably influences its crystallization kinetics, namely, the more homogeneous distribution of atoms results in a more sluggish nucleation behavior.展开更多
Fe40Ni40P14B6 bulk metallic glass rods have been prepared by water quenching the fluxed alloy. The deformation behavior was investigated by nanoindentation tests and compressing tests. The average hardness and elastic...Fe40Ni40P14B6 bulk metallic glass rods have been prepared by water quenching the fluxed alloy. The deformation behavior was investigated by nanoindentation tests and compressing tests. The average hardness and elastic modulus of the as-prepared Fe40Ni40P14B6 BMG (bulk metallic glass) measured by nanoindentation tests are 8.347 and 176.61 GPa respectively. The displace- ment-load curve shows “pop-in” characteristics which correspond to the loading rate bursts. Many shear bands around the indent were observed. The as-prepared Fe-based BMG exhibits a compressive plastic strain of 5.21%, which is much larger than that of other Fe-based glassy alloys and most of other BMGs.展开更多
The non-noble metal modified sulfated zirconia was found easy to deactivate.Herein,highly active and highly stable non-noble core-shell Ni-S_(2)O_(8)^(2−)/Al_(2)O_(3)@ZrO_(2) catalysts(Ni-SA@Z-x,x=Al content in wt%)ha...The non-noble metal modified sulfated zirconia was found easy to deactivate.Herein,highly active and highly stable non-noble core-shell Ni-S_(2)O_(8)^(2−)/Al_(2)O_(3)@ZrO_(2) catalysts(Ni-SA@Z-x,x=Al content in wt%)have been successfully prepared and investigated for n-pentane isomerization.The results showed that the core-shell Ni-SA@Z-30 provided a sustained high isopentane yield(63.1%)with little or no deactivation within 5000 min at a mild reaction pressure of 2.0 MPa,which can be attributed to the following factors:(i)carbon deposition was greatly suppressed by the large pore size and huge pore volume;(ii)the loss of sulfur entities was suppressed because the small and highly dispersed tetragonal ZrO_(2) particles can bond with the S species strongly;(iii)strong Brønsted acidity can be maintained well after the isomerization.The pore structures and acid nature of the core-shell Ni-SA@Z-x are entirely different from those of the normal structure Ni-S_(2)O_(8)^(2−)/ZrO_(2)-Al_(2)O_(3),even though the Al content and the compositions of the individual components are the same.The Al_(2)O_(3)cores endow the catalysts with high internal surface area and high mechanical strength.Meanwhile,the ZrO_(2) shell,which consists of more and smaller tetragonal ZrO_(2) particles because of the large surface area of the Al_(2)O_(3)core,promotes the formation of more stable sulfur species and stronger binding sites.展开更多
A molecular dynamics simulation study has been performed for the microstructure evolution in a liquid metal Ni system during crystallization process at two cooling rates by adopting the embedded atom method (EAM) mo...A molecular dynamics simulation study has been performed for the microstructure evolution in a liquid metal Ni system during crystallization process at two cooling rates by adopting the embedded atom method (EAM) model potential. The bond-type index method of Honeycutt-Andersen (HA) and a new cluster-type index method (CTIM-2) have been used to detect and analyse the microstructures in this system. It is demonstrated that the cooling rate plays a critical role in the microstructure evolution: below the crystallization temperature Tc, the effects of cooling rate are very remarkable and can be fully displayed. At different cooling rates of 2.0 × 10^13 K·s^-1 and 1.0 × 10^12 K·s^-1, two different kinds of crystal structures are obtained in the system. The first one is the coexistence of the hcp (expressed by (12 0 0 0 6 6) in CTIM-2) and the fcc (12 0 0 0 12 0) basic clusters consisting of 1421 and 1422 bond-types, and the hcp basic cluster becomes the dominant one with decreasing temperature, the second one is mainly the fcc (12 0 0 0 12 0) basic clusters consisting of 1421 bond-type, and their crystallization temperatures Tc would be 1073 and 1173 K, respectively.展开更多
Hydrotalcite precursors of La modified Ni-Al2O3 and Ni-SiO2 catalysts prepared by co-precipitation method and the catalytic activities were examined for the production of COx-free H2 by CH4 decomposition. Physico-chem...Hydrotalcite precursors of La modified Ni-Al2O3 and Ni-SiO2 catalysts prepared by co-precipitation method and the catalytic activities were examined for the production of COx-free H2 by CH4 decomposition. Physico-chemical characteristics of fresh, reduced and used catalysts were evaluated by XRD, TPR and O2 pulse chemisorptions, TEM and BET-SA techniques. XRD studies showed phases due to hydrotalcite-like precursors in oven dried form produced dispersed NiO species upon calcination in static air above 450 C. Raman spectra of deactivated samples revealed the presence of both ordered and disordered forms of carbon. Ni-La-Al2O3catalyst with a mole ratio of Ni : La : Al = 2 : 0.1 : 0.9 exhibited tremendously high longevity with a hydrogen production rate of 1300 molH2 mol 1 Ni. A direct relationship between Ni metal surface area and hydrogen yields was established.展开更多
The effects of Ce, Ti, Nb and C on the microstructures and mechanical properties of Ni Fe weld metal and the mechanism of their strengthening are discussed. Ce has the effect on graphite morphology and weld metal wit...The effects of Ce, Ti, Nb and C on the microstructures and mechanical properties of Ni Fe weld metal and the mechanism of their strengthening are discussed. Ce has the effect on graphite morphology and weld metal with spheroidal graphite has higher mechanical properties. The proper contents of Ti and Nb obviously increase the tensile strength of Ni Fe weld metal, which is mainly attributed to the austenite grain refining and second phase (TiC and NbC) strengthening. The excess C in weld metal results in increasing the quantity of carbide and graphite precipitating along the austenite grain boundary and decreasing the mechanical properties of Ni Fe weld metal.展开更多
The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studie...The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.展开更多
Microstructural evolution in weld metals was in-situ observed through utilizing a laser scanning confocal microscope at two cooling rates.The specimens with various nickel contents were adopted for the observation.In ...Microstructural evolution in weld metals was in-situ observed through utilizing a laser scanning confocal microscope at two cooling rates.The specimens with various nickel contents were adopted for the observation.In the specimen with low fraction of Ni(≤2 wt.%),granular bainite microstructure(i.e.broad surface relief)transformation from intragranular nucleation site was in-situ observed,while,lath bainite microstructure originating from grain boundary of austenite was in-situ observed for specimens with high mass percentage of Ni(≥4 wt.%).With increasing nickel content,the transformation temperature dropped.The prior austenite grain size was initially depressed and subsequently coarsened dramatically with the addition of Ni.The microstructure difference was ascribed to various nucleation sites and growth direction in the matrix.On account of those observations,not only the chemical component,cooling rate and microstructure were systematically correlated,but also the microstructural evolution was definite.展开更多
This study investigated the resistive switching characteristics of the Ni/HfCVPt structure for nonvolatile memory application.The Ni/HfO_2/Pt device showed bipolar resistive switching(RS) without a forming process, ...This study investigated the resistive switching characteristics of the Ni/HfCVPt structure for nonvolatile memory application.The Ni/HfO_2/Pt device showed bipolar resistive switching(RS) without a forming process, and the formation and rupture of conducting filaments are responsible for the resistive switching phenomenon.In addition,the device showed some excellent memory performances,including a large on/off ratio(〉 3×10~5),very good data retention(〉 10~3 s @ 200℃) and uniformity of switching parameters.Considering these results,the Ni/HfO_2/Pt device has the potential for nonvolatile memory applications.展开更多
We reported the effects of annealing temperatures on microstructure and electrochemical properties of perovskite-type oxide LaFeO3 prepared by stearic acid combustion method. X-Ray diffraction(XRD) patterns show tha...We reported the effects of annealing temperatures on microstructure and electrochemical properties of perovskite-type oxide LaFeO3 prepared by stearic acid combustion method. X-Ray diffraction(XRD) patterns show that the annealed LaFeO3 powder has orthorhombic structure. Scanning electron microscopy(SEM) and transmission electron microscopy(TEM) images show the presence of homogeneously dispersed, less aggregated, and small crystals(30--40 nm) at annealing temperatures of 500 and 600 ℃. However, as the annealing temperature was increased to 700 and 800 ℃, the crystals began to combine with each other and grew into further larger crystals(90--100 nm). The electrochemical performance of the annealed oxides was measured at 60 ℃ using chronopotentiometry, potentiodynamic polarization, and cyclic voltammetry. As the annealing temperature increased, the discharge capacity and anti-corrosion ability of the oxide electrode first increased and then decreased, reaching the optimum values at 600 ℃, with a maximum discharge capacity of 563 mA-h/g. The better electrochemical performance of LaFeO3 annealed at 600℃ could be ascribed to their smaller and more homogeneous crysals.展开更多
Aqueous metal batteries have attracted particular attention due to their low cost,environmental friendliness,and high safety.However,they still face challenges that hinder practical applications,including the oxygen a...Aqueous metal batteries have attracted particular attention due to their low cost,environmental friendliness,and high safety.However,they still face challenges that hinder practical applications,including the oxygen and hydrogen evolution and formation of the dendrite.Herein,we propose a novel hybrid-ion battery with Ni metal as the anode.Due to the electrostatic shielding effect of Li^(+),the surface of deposited Ni is smooth and dendrite-free,which enables an ultralong lifespan of over 4000 h and high coulombic efficiency over 99.5%.展开更多
基金Project (50804032) supported by the National Natural Science Foundation of ChinaProject (2008011046) supported by the Natural Science Foundation of Shanxi Province, ChinaProject (20080321036) supported by the Key Technologies R & D Program of Shanxi Province, China
文摘The microstructure of as-cast Zr60Al15Ni25 bulk metallic glass was investigated by high-resolution transmission electron microscopy. It is found that there exist numerous short-range order regions (SRORs) in the metallic glass though it is identified to be amorphous by X-ray diffraction method. Furthermore, the amorphous degree shows a close correlation with the microstructure of corresponding mother ingot. The crystallization kinetics was investigated by differential scanning calorimetry under isochronal and isothermal conditions. The results show that the crystallization is triggered by the growth of the pre-existing SRORs and the growth is three-dimension diffusion-controlled. The amorphous degree of Zr60Al15Ni25 bulk metallic glass considerably influences its crystallization kinetics, namely, the more homogeneous distribution of atoms results in a more sluggish nucleation behavior.
文摘Fe40Ni40P14B6 bulk metallic glass rods have been prepared by water quenching the fluxed alloy. The deformation behavior was investigated by nanoindentation tests and compressing tests. The average hardness and elastic modulus of the as-prepared Fe40Ni40P14B6 BMG (bulk metallic glass) measured by nanoindentation tests are 8.347 and 176.61 GPa respectively. The displace- ment-load curve shows “pop-in” characteristics which correspond to the loading rate bursts. Many shear bands around the indent were observed. The as-prepared Fe-based BMG exhibits a compressive plastic strain of 5.21%, which is much larger than that of other Fe-based glassy alloys and most of other BMGs.
文摘The non-noble metal modified sulfated zirconia was found easy to deactivate.Herein,highly active and highly stable non-noble core-shell Ni-S_(2)O_(8)^(2−)/Al_(2)O_(3)@ZrO_(2) catalysts(Ni-SA@Z-x,x=Al content in wt%)have been successfully prepared and investigated for n-pentane isomerization.The results showed that the core-shell Ni-SA@Z-30 provided a sustained high isopentane yield(63.1%)with little or no deactivation within 5000 min at a mild reaction pressure of 2.0 MPa,which can be attributed to the following factors:(i)carbon deposition was greatly suppressed by the large pore size and huge pore volume;(ii)the loss of sulfur entities was suppressed because the small and highly dispersed tetragonal ZrO_(2) particles can bond with the S species strongly;(iii)strong Brønsted acidity can be maintained well after the isomerization.The pore structures and acid nature of the core-shell Ni-SA@Z-x are entirely different from those of the normal structure Ni-S_(2)O_(8)^(2−)/ZrO_(2)-Al_(2)O_(3),even though the Al content and the compositions of the individual components are the same.The Al_(2)O_(3)cores endow the catalysts with high internal surface area and high mechanical strength.Meanwhile,the ZrO_(2) shell,which consists of more and smaller tetragonal ZrO_(2) particles because of the large surface area of the Al_(2)O_(3)core,promotes the formation of more stable sulfur species and stronger binding sites.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 50271026 and 50571037).
文摘A molecular dynamics simulation study has been performed for the microstructure evolution in a liquid metal Ni system during crystallization process at two cooling rates by adopting the embedded atom method (EAM) model potential. The bond-type index method of Honeycutt-Andersen (HA) and a new cluster-type index method (CTIM-2) have been used to detect and analyse the microstructures in this system. It is demonstrated that the cooling rate plays a critical role in the microstructure evolution: below the crystallization temperature Tc, the effects of cooling rate are very remarkable and can be fully displayed. At different cooling rates of 2.0 × 10^13 K·s^-1 and 1.0 × 10^12 K·s^-1, two different kinds of crystal structures are obtained in the system. The first one is the coexistence of the hcp (expressed by (12 0 0 0 6 6) in CTIM-2) and the fcc (12 0 0 0 12 0) basic clusters consisting of 1421 and 1422 bond-types, and the hcp basic cluster becomes the dominant one with decreasing temperature, the second one is mainly the fcc (12 0 0 0 12 0) basic clusters consisting of 1421 bond-type, and their crystallization temperatures Tc would be 1073 and 1173 K, respectively.
文摘Hydrotalcite precursors of La modified Ni-Al2O3 and Ni-SiO2 catalysts prepared by co-precipitation method and the catalytic activities were examined for the production of COx-free H2 by CH4 decomposition. Physico-chemical characteristics of fresh, reduced and used catalysts were evaluated by XRD, TPR and O2 pulse chemisorptions, TEM and BET-SA techniques. XRD studies showed phases due to hydrotalcite-like precursors in oven dried form produced dispersed NiO species upon calcination in static air above 450 C. Raman spectra of deactivated samples revealed the presence of both ordered and disordered forms of carbon. Ni-La-Al2O3catalyst with a mole ratio of Ni : La : Al = 2 : 0.1 : 0.9 exhibited tremendously high longevity with a hydrogen production rate of 1300 molH2 mol 1 Ni. A direct relationship between Ni metal surface area and hydrogen yields was established.
文摘The effects of Ce, Ti, Nb and C on the microstructures and mechanical properties of Ni Fe weld metal and the mechanism of their strengthening are discussed. Ce has the effect on graphite morphology and weld metal with spheroidal graphite has higher mechanical properties. The proper contents of Ti and Nb obviously increase the tensile strength of Ni Fe weld metal, which is mainly attributed to the austenite grain refining and second phase (TiC and NbC) strengthening. The excess C in weld metal results in increasing the quantity of carbide and graphite precipitating along the austenite grain boundary and decreasing the mechanical properties of Ni Fe weld metal.
文摘The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.
基金financially supported by National Natural Science Foundation of China (No.51675255)Pre-research of National Basic Research Program of China(2014CB660810)the Rose Willow Outstanding Individual Programs of Lanzhou University of Technology(J201203)
文摘Microstructural evolution in weld metals was in-situ observed through utilizing a laser scanning confocal microscope at two cooling rates.The specimens with various nickel contents were adopted for the observation.In the specimen with low fraction of Ni(≤2 wt.%),granular bainite microstructure(i.e.broad surface relief)transformation from intragranular nucleation site was in-situ observed,while,lath bainite microstructure originating from grain boundary of austenite was in-situ observed for specimens with high mass percentage of Ni(≥4 wt.%).With increasing nickel content,the transformation temperature dropped.The prior austenite grain size was initially depressed and subsequently coarsened dramatically with the addition of Ni.The microstructure difference was ascribed to various nucleation sites and growth direction in the matrix.On account of those observations,not only the chemical component,cooling rate and microstructure were systematically correlated,but also the microstructural evolution was definite.
文摘This study investigated the resistive switching characteristics of the Ni/HfCVPt structure for nonvolatile memory application.The Ni/HfO_2/Pt device showed bipolar resistive switching(RS) without a forming process, and the formation and rupture of conducting filaments are responsible for the resistive switching phenomenon.In addition,the device showed some excellent memory performances,including a large on/off ratio(〉 3×10~5),very good data retention(〉 10~3 s @ 200℃) and uniformity of switching parameters.Considering these results,the Ni/HfO_2/Pt device has the potential for nonvolatile memory applications.
基金Supported by the National Natural Science Foundation of China(Nos. 51771164, 51571173 and 51701175).
文摘We reported the effects of annealing temperatures on microstructure and electrochemical properties of perovskite-type oxide LaFeO3 prepared by stearic acid combustion method. X-Ray diffraction(XRD) patterns show that the annealed LaFeO3 powder has orthorhombic structure. Scanning electron microscopy(SEM) and transmission electron microscopy(TEM) images show the presence of homogeneously dispersed, less aggregated, and small crystals(30--40 nm) at annealing temperatures of 500 and 600 ℃. However, as the annealing temperature was increased to 700 and 800 ℃, the crystals began to combine with each other and grew into further larger crystals(90--100 nm). The electrochemical performance of the annealed oxides was measured at 60 ℃ using chronopotentiometry, potentiodynamic polarization, and cyclic voltammetry. As the annealing temperature increased, the discharge capacity and anti-corrosion ability of the oxide electrode first increased and then decreased, reaching the optimum values at 600 ℃, with a maximum discharge capacity of 563 mA-h/g. The better electrochemical performance of LaFeO3 annealed at 600℃ could be ascribed to their smaller and more homogeneous crysals.
基金supported by National Natural Science Foundation of China with grant no.51972142support from the Science and Technology Development Project,Jilin Province(grant nos.20180101211JC and 20190701020GH)the Fundamental Research Funds for the Central Universities.
文摘Aqueous metal batteries have attracted particular attention due to their low cost,environmental friendliness,and high safety.However,they still face challenges that hinder practical applications,including the oxygen and hydrogen evolution and formation of the dendrite.Herein,we propose a novel hybrid-ion battery with Ni metal as the anode.Due to the electrostatic shielding effect of Li^(+),the surface of deposited Ni is smooth and dendrite-free,which enables an ultralong lifespan of over 4000 h and high coulombic efficiency over 99.5%.