A new type of lightweight AlNiLa medium entropy amorphous alloy composite ribbons(labled as MEAAC ribbons)were prepared by vacuum arc melting technology and high-speed single roller meltspinning method.The microstruct...A new type of lightweight AlNiLa medium entropy amorphous alloy composite ribbons(labled as MEAAC ribbons)were prepared by vacuum arc melting technology and high-speed single roller meltspinning method.The microstructure and thermal stability of MEAAC ribbons were examined using X-ray diffraction,differential scanning calorimeter,and scanning electron microscope.Meanwhile,the hardness and surface roughness of these ribbons were measured by Vickers microhardness tester and atomic force microscope.The potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS)were applied to investigate the corrosion behavior of these MEAAC ribbons in simulated seawater(3.5wt%NaCl corrosive solution)at room temperature.The results demonstrate that AlNiLa MEAAC ribbons in the as-received state are mainly composed of amorphous phase and intermetallic compounds.The hardness values of all melt-spun ribbons are above 310 HV_(0.1).With the increase of Al content,the linear polarization resistances of four various AlNiLa MEAAC ribbons are negligibly different numerically.It is also found that Al_(45)Ni_(27.5)La_(27.5) MEAAC ribbons have the most positive corrosion potential and the smallest corrosion current density at the same time;hence it may be a kind of potential material for metal surface protection in harsh ocean environment.展开更多
In this paper, the synthetic effect ofCr, Mo and Y on corrosion resistance was explored, and the YCr/Mo value was employed to evaluate the corrosion resistance. The composition of amorphous alloy was designed by mixin...In this paper, the synthetic effect ofCr, Mo and Y on corrosion resistance was explored, and the YCr/Mo value was employed to evaluate the corrosion resistance. The composition of amorphous alloy was designed by mixing the Fe41Co7Cr15Mo14C15B6Y2 (BMG1) with good glass forming ability (GFA) and Fe50Cr22B23Ni5.4 with a high corrosion resistance at 9:1 ratio. At the same time, the contents of Y, Mo and Cr were fine-tuned. The electrochemical tests demonstrated that the passivation current density decreased with the increase of the yCr/Mo value. The passivation current density of Fe-based amorphous alloy was reduced by about half an order of magnitude. The fitting result showed that the logarithm ofpassivation current density (I) and the YCr/Mo value (X) were logarithmic relationship, and the fitting equation was I=-5.649+4.904× 1015 e 17.52x. The X-ray photoelectron spectroscopy (XPS) results showed that the yC,/Mo value played a key role in stability of passive films. When the yCr/Mo value Was low, the Cr6+ ion, Mo6+ ion were enriched in the initial stage of passivation process, then leading to the increase passivation current density. However, when the YCr/Mo value was high, the low-valence Fe2-, Cr3+, and Mo4+ ion were enriched more easily, which result in small passivation current densities and more stable passive films.展开更多
In the present paper, one hundred cluster models NinBP (n = 1-6) have been designed and studied by density functional theory (DFT) to get an insight into the local structure, catalytic properties and sulfur resist...In the present paper, one hundred cluster models NinBP (n = 1-6) have been designed and studied by density functional theory (DFT) to get an insight into the local structure, catalytic properties and sulfur resistibility of amorphous alloy Ni-B-P. The configurations in triplet state are found more stable than those in the singlet state. It is found: that as the content of Ni in the clusters increases, the value of Fermi level in clusters fluctuated, which shows that the content of Ni can influence the Fermi level to a certain extent. Based on the Fermi level and DOS, we consider the activity of catalyst in hydrogenation reaction is the best in cluster Ni3BP. On the basis of the charge of clusters NinBP (n = 1 -6), we conclude the amorphous alloy Ni-B-P with high Ni content has better sulfur resistibility and the best hydrogenation activity, strong sulfur resistibility appears in clusters Ni3BP, and the amorphous alloy Ni60B20P20 with similar proportion is expected to prepare in the future.展开更多
A support(denoted AM) was prepared using pseudo-boehmite and mordenite.Ni-B and NiPtB amorphous catalysts were prepared on the support by the impregnation method followed by chemical reduction with a KBH4 solution.And...A support(denoted AM) was prepared using pseudo-boehmite and mordenite.Ni-B and NiPtB amorphous catalysts were prepared on the support by the impregnation method followed by chemical reduction with a KBH4 solution.And the catalysts were characterized by X-ray diffraction(XRD),environment scanning electron microscope(ESEM),inductively coupled plasma(ICP),H2-temperature programmed reduction(H2-TPR),differential thermal analysis(DTA),and BET.Benzene hydrogenation was used as a probe reaction to evaluate the effect of addition of small quantities of Pt on the NiB/AM catalyst.The results show that Pt can promote the reduction of NiO and the formation of active sites,leading to smaller catalyst particles and better dispersion of active metal particles on the support.The catalytic activity,sulfur resistance and thermal stability were remarkably improved by Pt doping of the NiB/AM catalyst.展开更多
The influence of Nd addition on the glass-forming ability(GFA), microhardness, and corrosion resistance of Mg_(60-x)Cu_(40)Nd_x(x = 5, 10, 15, 20, and 25, at%) alloys were investigated by differential scanning calorim...The influence of Nd addition on the glass-forming ability(GFA), microhardness, and corrosion resistance of Mg_(60-x)Cu_(40)Nd_x(x = 5, 10, 15, 20, and 25, at%) alloys were investigated by differential scanning calorimetry, Vickers-type hardness tests, and electrochemical methods. The results suggest that the GFA and microhardness of the amorphous alloys increase until the Nd content reaches 20at%. The corrosion potential and corrosion current density obtained from the Tafel curves indicate that the Mg_(35)Cu_(40)Nd_(25) ternary alloy exhibits the best corrosion resistance among the investigated alloys. Notably, nanoporous copper(NPC) was synthesized through a single-step dealloying of Mg_(60-x)Cu_(40)Nd_x(x = 5, 10, 15, 20, and 25) ternary alloys in 0.04 mol·L^(-1) H_2SO_4 solution under free corrosion conditions. The influence of dealloying process parameters, such as dealloying time and temperature, on the microstructure of the ribbons was also studied using the surface diffusivity theory. The formation mechanism of dealloyed samples with a multilayered structure was also discussed.展开更多
An accurate four-line ac electrical resistance measurement (ERM)apparatus was developed. By using the ERM the crystallization kinetics of amorphous Ni80P20, FeZr2, Fe86B14 alloys were investigated. The experimental re...An accurate four-line ac electrical resistance measurement (ERM)apparatus was developed. By using the ERM the crystallization kinetics of amorphous Ni80P20, FeZr2, Fe86B14 alloys were investigated. The experimental results show that the ERM can identify the early stage of crystallization in amorphous alloys. The ERM detects a crystallization temperature range obviously wider than the DSC does, indicating that the ERM is more sensitive to the structure evolution in crystallization. For the eutectic or polymorphic crystallization, three distinct processes can be identified from the measured resistance variation: (i) crystal nucleation, (ii) subsequent growth of crystal nuclei, and (iii) coarsening of the crystallites. In the early stage of the primary crystallization, the ERM results reflect the nucleation information as well.展开更多
A new concept of lightweight structure,namely amorphous-alloy-reinforced perforated armor(ARPA)consisting of the amorphous alloy coating and perforated metal substrate plate,is proposed.The ballistic performance of th...A new concept of lightweight structure,namely amorphous-alloy-reinforced perforated armor(ARPA)consisting of the amorphous alloy coating and perforated metal substrate plate,is proposed.The ballistic performance of the ARPA is investigated numerically.The failure modes of ARPA and projectiles are identified,and the defeating mechanism of the ARPA is explored.It is shown that the amorphous alloy coating is helpful for enhancing the target’s ballistic performance by seriously eroding and fracturing the penetrators.The effects of coating thickness,initial impact velocity and impact angle are also discussed for the target’s ballistic performance.The optimal design of coating thickness may be necessary for enhancing the ballistic resistance of ARPAs.展开更多
In this work,amorphous Zr_(55)Al_(10)Ni_(5)Cu_(30)alloy thin film was prepared on D36 steel substrate by magnetron sputtering method.The film was characterized by scanning electron microscopy(SEM),X-ray diffraction(XR...In this work,amorphous Zr_(55)Al_(10)Ni_(5)Cu_(30)alloy thin film was prepared on D36 steel substrate by magnetron sputtering method.The film was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),atomic force microscopy(AFM),hardness tester and nano indentation.Corrosion behavior of the film was investigated in 3.5%NaCl aqueous solutions by an electrochemical method.At room temperature,the amorphous alloy film was formed completely after sputtering for 5 h.The surface morphology of the amorphous alloy film was uniform and smooth.Formation of the amorphous alloy film improved the microhardness and corrosion resistance of the D36 substrate.The amorphous alloy film(prepared at room temperature for 5 h)exhibited good adhesion strength with the substrate.The as-sputtered sample exhibited a crevice corrosion trend when the sputtering time was too short(1 h)or too long(10 h).展开更多
A new technique of electroplating amorphous Fe-Ni-W alloy deposits was proposed.The structure and morphology o Fe-Ni-W alloy deposit were detected by XRD and SEM.The friction and wear behavior of Fe-Ni-W alloy deposit...A new technique of electroplating amorphous Fe-Ni-W alloy deposits was proposed.The structure and morphology o Fe-Ni-W alloy deposit were detected by XRD and SEM.The friction and wear behavior of Fe-Ni-W alloy deposit were studied and compared with that of chromium deposit.The corrosion properties against 5% sodium chloride,5% sulfuric acid and 5% sodium hydroxide were also discussed.The experimental results indicate that Fe-Ni-W alloy deposits have superior properties against wea than hard chromium deposits under dry sliding condition.Under oil sliding condition,except their better wear resistance,the deposits can protect their counterparts against wear.The deposits plated on brass and AISI 1045 steel show good behavior against corrosion o 5% sodium chloride,5% sulfuric acid and 5% sodium hydroxide.The bath of electroplating amorphous Fe-Ni-W alloy deposits is environmentally friendly and would find widely use in industry.展开更多
Amorphous ferromagnetic alloy has excellent magnetism, and its resistivity is oneor two orders of magnitude higher than that of crystal alloy of the same composition.It is extensively applied in America, Japan, German...Amorphous ferromagnetic alloy has excellent magnetism, and its resistivity is oneor two orders of magnitude higher than that of crystal alloy of the same composition.It is extensively applied in America, Japan, Germany, France etc., since it can beused as the material to make the core in a transformer to reduce the energy loss andenhance the working frequency.展开更多
The amorphous Ti_(l_x)Pd_x alloys within a wider composition range of 0.25<x<0.6 have been prepared using sputter-deposition method on the liquid-nitrogen-cooled substrates.The for- mation of amorphous Ti-Pd all...The amorphous Ti_(l_x)Pd_x alloys within a wider composition range of 0.25<x<0.6 have been prepared using sputter-deposition method on the liquid-nitrogen-cooled substrates.The for- mation of amorphous Ti-Pd alloys relates to the topologically close-packed intermetallic compounds existing in the equilibrium phase diagram.These amorphous Ti-Pd alloys are identified by differential scanning calorimetry that the crystallization begins at about 700 K. The insensitive dependence of the crystallization temperature on composition of the alloys is explained with a model proposed by Miedema and Buschow.The electric resistivity of the amorphous Ti-Pd alloys in the range of 4.2 to 270 K decreases monotonously with in- creasing temperature.展开更多
There remains growing interest in magnesium(Mg)and its alloys,as they are the lightest structural metallic materials and potential metallic biomaterials.In spite of the greatest historical Mg usage at present,the wide...There remains growing interest in magnesium(Mg)and its alloys,as they are the lightest structural metallic materials and potential metallic biomaterials.In spite of the greatest historical Mg usage at present,the wider use of Mg alloys remains restricted by the poor corrosion resistance.A nano amorphous film,as the composition of Al2O3,had now been deposited on the AZ31 Mg alloy substrate by atomic layer deposition(ALD).Grazing incidence X-ray diffraction(GIXRD),X-ray reflectivity(XRR),X-ray photoelectron spectroscopy(XPS),atomic force microscope(AFM)and scanning electron microscopy(SEM)had been employed to identify the chemical compositions,microstructure and Al2O3/Mg interface of specimens firstly.Then corrosion behavior had been evaluated by neutral salt spray test and electrochemical measurement.The results showed that nano amorphous film made a homogeneous cover on Mg alloy.The film could improve the corrosion resistance of Mg alloy greatly,not only with a positive shift in Ecorr and a decrease in icorr,but also with a more uniform corroded mode.Furthermore,the roughness was found to be an important factor for corrosion resistant,in the way that rougher surface was corroded worse,and greater improvement would be in corrosion resistant after nano amorphous film deposition.展开更多
A set of fracture device was designed on the basis of traditional scratching-electrode technology and used to study the passivation process of two magnetron-sputtered stainless sleel coatings (amorphous and crystallin...A set of fracture device was designed on the basis of traditional scratching-electrode technology and used to study the passivation process of two magnetron-sputtered stainless sleel coatings (amorphous and crystalline struture). The results of fracture tests in 3.5 % NaCl aqueous solution show that the amorphous alloy has a high bare surface reactivity and a high passive rate in comparison with the crystalline alloy. The effect of structure on corrosion resistance is also discussed. The excellent corrosion resistance of amorphous alloy is considered to be partly attributed to its great passivation ability.展开更多
The electrical transport properties of (Ni0.8Nb0.2)100-xZrx (x = 30, 40 and 50) amorphous ribbons and hydrogen charged specimens were investigated. The amorphous ribbons indicated a negative coefficient in the tempera...The electrical transport properties of (Ni0.8Nb0.2)100-xZrx (x = 30, 40 and 50) amorphous ribbons and hydrogen charged specimens were investigated. The amorphous ribbons indicated a negative coefficient in the temperature dependence of their electrical resistivity as well as the typical transport properties of the amorphous alloys with comparatively high values of electrical resistivity, ρ. The normalized temperature coefficient of the resistivity (TCR ≡ 1/ρ300K·dρ/dT) tended to increase with increasing x in the temperature range of 100-300 K. These behaviors would suggest that the transport properties of the present amorphous ribbons were governed by temperature variation of the Debye-Waller factor, not by electron-phonon scattering. The hydrogen charged ribbons obtained by an electrochemical method also showed similar electrical resistivity behaviors as a function of the temperature. However, TCR of x = 40 with hydrogen charged ribbon, in which the amount of absorbed hydrogen was about 14 at%, increased about three times more than that of the pre-charged amorphous ribbon.展开更多
基金by the National Key R&D Program of China(No.2018YFC1902400)the National Natural Science Foundation of China(No.51975582)the Natural Science Foundation of Beijing,China(No.2212055)。
文摘A new type of lightweight AlNiLa medium entropy amorphous alloy composite ribbons(labled as MEAAC ribbons)were prepared by vacuum arc melting technology and high-speed single roller meltspinning method.The microstructure and thermal stability of MEAAC ribbons were examined using X-ray diffraction,differential scanning calorimeter,and scanning electron microscope.Meanwhile,the hardness and surface roughness of these ribbons were measured by Vickers microhardness tester and atomic force microscope.The potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS)were applied to investigate the corrosion behavior of these MEAAC ribbons in simulated seawater(3.5wt%NaCl corrosive solution)at room temperature.The results demonstrate that AlNiLa MEAAC ribbons in the as-received state are mainly composed of amorphous phase and intermetallic compounds.The hardness values of all melt-spun ribbons are above 310 HV_(0.1).With the increase of Al content,the linear polarization resistances of four various AlNiLa MEAAC ribbons are negligibly different numerically.It is also found that Al_(45)Ni_(27.5)La_(27.5) MEAAC ribbons have the most positive corrosion potential and the smallest corrosion current density at the same time;hence it may be a kind of potential material for metal surface protection in harsh ocean environment.
基金Project supported by the National Natural Science Foundation of China(51261021)Science and Technology Landing Plan Project of Jiangxi Province(KJLD13056)
文摘In this paper, the synthetic effect ofCr, Mo and Y on corrosion resistance was explored, and the YCr/Mo value was employed to evaluate the corrosion resistance. The composition of amorphous alloy was designed by mixing the Fe41Co7Cr15Mo14C15B6Y2 (BMG1) with good glass forming ability (GFA) and Fe50Cr22B23Ni5.4 with a high corrosion resistance at 9:1 ratio. At the same time, the contents of Y, Mo and Cr were fine-tuned. The electrochemical tests demonstrated that the passivation current density decreased with the increase of the yCr/Mo value. The passivation current density of Fe-based amorphous alloy was reduced by about half an order of magnitude. The fitting result showed that the logarithm ofpassivation current density (I) and the YCr/Mo value (X) were logarithmic relationship, and the fitting equation was I=-5.649+4.904× 1015 e 17.52x. The X-ray photoelectron spectroscopy (XPS) results showed that the yC,/Mo value played a key role in stability of passive films. When the yCr/Mo value Was low, the Cr6+ ion, Mo6+ ion were enriched in the initial stage of passivation process, then leading to the increase passivation current density. However, when the YCr/Mo value was high, the low-valence Fe2-, Cr3+, and Mo4+ ion were enriched more easily, which result in small passivation current densities and more stable passive films.
基金University of Science and Technology Liaoning Research Project (No. 2003001)
文摘In the present paper, one hundred cluster models NinBP (n = 1-6) have been designed and studied by density functional theory (DFT) to get an insight into the local structure, catalytic properties and sulfur resistibility of amorphous alloy Ni-B-P. The configurations in triplet state are found more stable than those in the singlet state. It is found: that as the content of Ni in the clusters increases, the value of Fermi level in clusters fluctuated, which shows that the content of Ni can influence the Fermi level to a certain extent. Based on the Fermi level and DOS, we consider the activity of catalyst in hydrogenation reaction is the best in cluster Ni3BP. On the basis of the charge of clusters NinBP (n = 1 -6), we conclude the amorphous alloy Ni-B-P with high Ni content has better sulfur resistibility and the best hydrogenation activity, strong sulfur resistibility appears in clusters Ni3BP, and the amorphous alloy Ni60B20P20 with similar proportion is expected to prepare in the future.
基金Supported by the Overseas Scholars of Heilongjiang Province of China (1151hq006)
文摘A support(denoted AM) was prepared using pseudo-boehmite and mordenite.Ni-B and NiPtB amorphous catalysts were prepared on the support by the impregnation method followed by chemical reduction with a KBH4 solution.And the catalysts were characterized by X-ray diffraction(XRD),environment scanning electron microscope(ESEM),inductively coupled plasma(ICP),H2-temperature programmed reduction(H2-TPR),differential thermal analysis(DTA),and BET.Benzene hydrogenation was used as a probe reaction to evaluate the effect of addition of small quantities of Pt on the NiB/AM catalyst.The results show that Pt can promote the reduction of NiO and the formation of active sites,leading to smaller catalyst particles and better dispersion of active metal particles on the support.The catalytic activity,sulfur resistance and thermal stability were remarkably improved by Pt doping of the NiB/AM catalyst.
基金financially supported by the National Natural Science Foundation of China (Nos. 51401085 and 51202088)the Shandong Province Higher Educational Science and Technology Program (No. J14LA06)
文摘The influence of Nd addition on the glass-forming ability(GFA), microhardness, and corrosion resistance of Mg_(60-x)Cu_(40)Nd_x(x = 5, 10, 15, 20, and 25, at%) alloys were investigated by differential scanning calorimetry, Vickers-type hardness tests, and electrochemical methods. The results suggest that the GFA and microhardness of the amorphous alloys increase until the Nd content reaches 20at%. The corrosion potential and corrosion current density obtained from the Tafel curves indicate that the Mg_(35)Cu_(40)Nd_(25) ternary alloy exhibits the best corrosion resistance among the investigated alloys. Notably, nanoporous copper(NPC) was synthesized through a single-step dealloying of Mg_(60-x)Cu_(40)Nd_x(x = 5, 10, 15, 20, and 25) ternary alloys in 0.04 mol·L^(-1) H_2SO_4 solution under free corrosion conditions. The influence of dealloying process parameters, such as dealloying time and temperature, on the microstructure of the ribbons was also studied using the surface diffusivity theory. The formation mechanism of dealloyed samples with a multilayered structure was also discussed.
基金This work was supported by the Chinese Academy of Sciences and the National Natural Science Foundation of China (Grant No. 59625101).
文摘An accurate four-line ac electrical resistance measurement (ERM)apparatus was developed. By using the ERM the crystallization kinetics of amorphous Ni80P20, FeZr2, Fe86B14 alloys were investigated. The experimental results show that the ERM can identify the early stage of crystallization in amorphous alloys. The ERM detects a crystallization temperature range obviously wider than the DSC does, indicating that the ERM is more sensitive to the structure evolution in crystallization. For the eutectic or polymorphic crystallization, three distinct processes can be identified from the measured resistance variation: (i) crystal nucleation, (ii) subsequent growth of crystal nuclei, and (iii) coarsening of the crystallites. In the early stage of the primary crystallization, the ERM results reflect the nucleation information as well.
基金The authors gratefully acknowledge the financial support of NSFC(11972281,11872291,11572234,11502189)Opening Project of Science and Technology on Transient Impact Laboratory(614260601010117)+1 种基金Natural Science Basic Research Plan in Shaanxi Province of China(2020JM-034)China Postdoctoral Science Foundation funded project(2018M643621).
文摘A new concept of lightweight structure,namely amorphous-alloy-reinforced perforated armor(ARPA)consisting of the amorphous alloy coating and perforated metal substrate plate,is proposed.The ballistic performance of the ARPA is investigated numerically.The failure modes of ARPA and projectiles are identified,and the defeating mechanism of the ARPA is explored.It is shown that the amorphous alloy coating is helpful for enhancing the target’s ballistic performance by seriously eroding and fracturing the penetrators.The effects of coating thickness,initial impact velocity and impact angle are also discussed for the target’s ballistic performance.The optimal design of coating thickness may be necessary for enhancing the ballistic resistance of ARPAs.
基金financially supported by the National Natural Science Foundation of China(No.51771131)。
文摘In this work,amorphous Zr_(55)Al_(10)Ni_(5)Cu_(30)alloy thin film was prepared on D36 steel substrate by magnetron sputtering method.The film was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),atomic force microscopy(AFM),hardness tester and nano indentation.Corrosion behavior of the film was investigated in 3.5%NaCl aqueous solutions by an electrochemical method.At room temperature,the amorphous alloy film was formed completely after sputtering for 5 h.The surface morphology of the amorphous alloy film was uniform and smooth.Formation of the amorphous alloy film improved the microhardness and corrosion resistance of the D36 substrate.The amorphous alloy film(prepared at room temperature for 5 h)exhibited good adhesion strength with the substrate.The as-sputtered sample exhibited a crevice corrosion trend when the sputtering time was too short(1 h)or too long(10 h).
基金Project(04GK1007) supported by the Science and Technology Office of Hunan Province,China
文摘A new technique of electroplating amorphous Fe-Ni-W alloy deposits was proposed.The structure and morphology o Fe-Ni-W alloy deposit were detected by XRD and SEM.The friction and wear behavior of Fe-Ni-W alloy deposit were studied and compared with that of chromium deposit.The corrosion properties against 5% sodium chloride,5% sulfuric acid and 5% sodium hydroxide were also discussed.The experimental results indicate that Fe-Ni-W alloy deposits have superior properties against wea than hard chromium deposits under dry sliding condition.Under oil sliding condition,except their better wear resistance,the deposits can protect their counterparts against wear.The deposits plated on brass and AISI 1045 steel show good behavior against corrosion o 5% sodium chloride,5% sulfuric acid and 5% sodium hydroxide.The bath of electroplating amorphous Fe-Ni-W alloy deposits is environmentally friendly and would find widely use in industry.
文摘Amorphous ferromagnetic alloy has excellent magnetism, and its resistivity is oneor two orders of magnitude higher than that of crystal alloy of the same composition.It is extensively applied in America, Japan, Germany, France etc., since it can beused as the material to make the core in a transformer to reduce the energy loss andenhance the working frequency.
文摘The amorphous Ti_(l_x)Pd_x alloys within a wider composition range of 0.25<x<0.6 have been prepared using sputter-deposition method on the liquid-nitrogen-cooled substrates.The for- mation of amorphous Ti-Pd alloys relates to the topologically close-packed intermetallic compounds existing in the equilibrium phase diagram.These amorphous Ti-Pd alloys are identified by differential scanning calorimetry that the crystallization begins at about 700 K. The insensitive dependence of the crystallization temperature on composition of the alloys is explained with a model proposed by Miedema and Buschow.The electric resistivity of the amorphous Ti-Pd alloys in the range of 4.2 to 270 K decreases monotonously with in- creasing temperature.
基金This work was supported by National Key Research and Development Program(Nos.2016YFB0701201,2016YFB0701203)National Natural Science Foundation of China(Nos.51671101)+3 种基金Domain Foundation of Equipment Advance Research of 13th Five-year Plan(No.61409220118)Natural Science Foundation of JiangXi Province(Nos.20171BCD40003)Key Research and Development Program of JiangXi Province(No GJJ150010)Nanchang University Graduate Innovation Special Fund(No.CX2018038).
文摘There remains growing interest in magnesium(Mg)and its alloys,as they are the lightest structural metallic materials and potential metallic biomaterials.In spite of the greatest historical Mg usage at present,the wider use of Mg alloys remains restricted by the poor corrosion resistance.A nano amorphous film,as the composition of Al2O3,had now been deposited on the AZ31 Mg alloy substrate by atomic layer deposition(ALD).Grazing incidence X-ray diffraction(GIXRD),X-ray reflectivity(XRR),X-ray photoelectron spectroscopy(XPS),atomic force microscope(AFM)and scanning electron microscopy(SEM)had been employed to identify the chemical compositions,microstructure and Al2O3/Mg interface of specimens firstly.Then corrosion behavior had been evaluated by neutral salt spray test and electrochemical measurement.The results showed that nano amorphous film made a homogeneous cover on Mg alloy.The film could improve the corrosion resistance of Mg alloy greatly,not only with a positive shift in Ecorr and a decrease in icorr,but also with a more uniform corroded mode.Furthermore,the roughness was found to be an important factor for corrosion resistant,in the way that rougher surface was corroded worse,and greater improvement would be in corrosion resistant after nano amorphous film deposition.
文摘A set of fracture device was designed on the basis of traditional scratching-electrode technology and used to study the passivation process of two magnetron-sputtered stainless sleel coatings (amorphous and crystalline struture). The results of fracture tests in 3.5 % NaCl aqueous solution show that the amorphous alloy has a high bare surface reactivity and a high passive rate in comparison with the crystalline alloy. The effect of structure on corrosion resistance is also discussed. The excellent corrosion resistance of amorphous alloy is considered to be partly attributed to its great passivation ability.
文摘The electrical transport properties of (Ni0.8Nb0.2)100-xZrx (x = 30, 40 and 50) amorphous ribbons and hydrogen charged specimens were investigated. The amorphous ribbons indicated a negative coefficient in the temperature dependence of their electrical resistivity as well as the typical transport properties of the amorphous alloys with comparatively high values of electrical resistivity, ρ. The normalized temperature coefficient of the resistivity (TCR ≡ 1/ρ300K·dρ/dT) tended to increase with increasing x in the temperature range of 100-300 K. These behaviors would suggest that the transport properties of the present amorphous ribbons were governed by temperature variation of the Debye-Waller factor, not by electron-phonon scattering. The hydrogen charged ribbons obtained by an electrochemical method also showed similar electrical resistivity behaviors as a function of the temperature. However, TCR of x = 40 with hydrogen charged ribbon, in which the amount of absorbed hydrogen was about 14 at%, increased about three times more than that of the pre-charged amorphous ribbon.