The high-temperature compressive deformation behavior of medium manganese steel using a four-roll reversible rolling mill is investigated,revealing the effects of different Mn contents on the thermal deformation behav...The high-temperature compressive deformation behavior of medium manganese steel using a four-roll reversible rolling mill is investigated,revealing the effects of different Mn contents on the thermal deformation behavior of oxidation products in the alloy.It is found that within the experimental temperature range,the higher the deformation temperature,the better the plasticity of the oxidation products.It was observed that increasing the Mn content refines the grains,enhances the deformation ability of the oxidation products,and improves the flatness of the interfaces.Since(Fe,Mn)O has a similar crystal structure to FeO,the addition of Mn refines the grains of(Fe,Mn)O,causing the deformation to be distributed across more grains under the same deformation amount,and thereby improving its plasticity.At the interface between Fe-Mn alloy oxidation products and the matrix,there exists a spinel-phase solid solution,which can deform together with the oxidation products and the matrix at high temperatures.It was found that with increasing the Mn content,the size and number of pores between the spinel phases increased.First-principles simulation calculations were used to verify this,showing that Mn promotes the generation of vacancies.The greater number of pores in the spinel phase can effectively relieve the compressive stress caused by rolling deformation,thereby improving the deformation capability of the oxidation products at the interface.展开更多
To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretre...To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.展开更多
The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical pr...The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical properties,can significantly enhance the oxidation resistance of Mg alloys.Based on our previous study,we conclude that REs such as Gd,Y,and Ce enhance the oxidation resistance of Mg-RE alloys.This article comprehensively reviews recent research progress on high-temperature oxidation behavior and the potential mechanism in Mg-RE alloys.Based on the thermodynamic and kinetic analyses,the evolution of the complex oxide system formed during the high-temperature oxidation of Mg-RE alloys is first summarized.The diffusion behavior and concentration control mechanisms of REs during the oxidation process and how these mechanisms affect the sustained growth of the oxide film and antioxidant properties were elucidated.Moreover,the different structures of the oxide films were classified,and their properties were discussed.Finally,this paper introduces the applications of commonly used REs in Mg alloys and frontier research on their oxidation mechanisms.Based on the above review,we propose that future research perspectives can be explored in terms of expanding the experimental temperature range for oxidation tests,optimizing the chemical composition by adding trace REs to study their synergistic mechanism,revealing the underlying oxidation mechanism through advanced in situ microscopic characterization methods,and investigating the mechanical properties of oxide films using diverse approaches.展开更多
TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
The high-temperature oxidation resistance of AISI 321 stainless steel used in solar thermal power heat exchangers determines its service life.In this study,aluminizing and subsequent laser shock peening(LSP)treatments...The high-temperature oxidation resistance of AISI 321 stainless steel used in solar thermal power heat exchangers determines its service life.In this study,aluminizing and subsequent laser shock peening(LSP)treatments were employed to improve the high-temperature oxidation resistance of AISI 321 stainless steel at 620°C.These two treatments decreased the oxidation rate of AISI 321 steel.Specifically,the optimal oxidation resistance was observed in aluminized steel before oxidation for 144 h owing to the increased entropy of the LSP-treated specimen.After 144 h,LSP-treated steel achieved the best oxidation resistance because of the formation of a protectiveα-Al2O3film.Moreover,the large amount of subgrain boundaries formed on the aluminized layer of the LSP-treated samples could act as short-circuit paths for the outward diffusion of Al,facilitating the rapid nucleation ofα-Al2O3.Meanwhile,the aluminized layer could isolate the contact between the oxidation environment and matrix,thereby decreasing the oxidation rate.Furthermore,the minimum oxidation parabolic constant was calculated for LSP-treated steel(6.45787×10^(-14)),which was 69.18%and 36.36%that of aluminized and 321 steel,respectively,during the entire oxidation process.Therefore,the combination of aluminizing and LSP treatments can improve the high-temperature oxidation resistance of 321 stainless steel,providing a new idea for its surface treatment to achieve a long service life at high temperatures.展开更多
3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was...3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was investigated using impedance spectroscopy （IS） combined with scanning electron microscopy （SEM）, Raman spectroscopy and X-ray diffractometry （XRD）. Various electrical responses observed in the impedance spectra corresponding to GY-YSZ grains and grain boundaries were explained using circuit modeling. The change in the conduction mechanism of GY-YSZ was found to be related to the O^2- vacancy and lattice distortion due to the stabilizer diffusion during the oxidation. The results also suggested that the specific oxidation information about the GY-YSZ grains and grain boundaries should be acquired at a moderate measurement temperature, which was related to the resistance value in the impedance spectra. The resistance values of the GY-YSZ grains and grain boundaries should be measured at 200 ℃ and 300 ℃, respectively.展开更多
Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,a...Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.展开更多
Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose har...Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose hardness is 65 HRC and flexural strength is 1450 MPa.The high-temperature oxidation mechanism of TiC-based cermets was investigated through an X-ray diffractometer and scanning electron microscope.The added elements Ni and Cr along with their solid solutions not only bond with the hard phase TiC to ensure the physical performance of the cermet,but also impede the internal diffusion during oxidation by forming a dense composite oxide layer,thereby enhancing the oxidation resistance.The TiC-NiCr cermet exhibits a dense protective oxide layer at 900℃ and can endure continuous oxidation for approximately 1000 h.A methodology for fabricating TiC-NiCr metal matrix composites is proposed,and their oxidation resistance is evaluated,providing a theoretical and practical basis for simultaneously enhancing the mechanical properties and oxidation resistance and reducing production costs.展开更多
To improve the high-temperature oxidation resistance of TiAlNb9 alloy,a Cr-Al-Y co-deposition coating was prepared on the alloy surface by the pack cementation method.The microstructure of the coating was analyzed by ...To improve the high-temperature oxidation resistance of TiAlNb9 alloy,a Cr-Al-Y co-deposition coating was prepared on the alloy surface by the pack cementation method.The microstructure of the coating was analyzed by scanning electron microscope,energy dispersive spectrometer,and X-ray diffractometer,and the high-temperature oxidation properties of the substrate and coating at 1273 K were compared and studied.The results show that the Cr-Al-Y coating is about 30μm in thickness,and it has a dense structure and good film-substrate bonding.The coating includes an outer layer composed of TiCr_(2),TiCr,Ti_(4)Cr,and(Ti,Nb)Cr_(4) phases as well as an inner layer composed of Ti_(2)Al,and Nb-richγ-TiAl interdiffusion zone.The TiAlNb9 substrate forms an oxide layer composed of TiO_(2) and Al_(2)O_(3) at 1273 K.Due to its loose and porous structure,TiO_(2) oxide film cannot effectively isolate the internal diffusion of element O,resulting in continuous oxidation damage to the substrate.The Cr-Al-Y co-deposition coating forms a dense Cr_(2)O_(3) and Al_(2)O_(3) oxide layer during oxidation,effectively preventing the internal diffusion of element O and significantly improving the high-temperature oxidation resistance of the substrate alloy.展开更多
To improve the high-temperature service properties of coppery tuyere,Co06 coating with a Ni60A interlayer was prepared on copper by plasma cladding.Ni60A interlayer acted as a bridge to promote the element diffusion,t...To improve the high-temperature service properties of coppery tuyere,Co06 coating with a Ni60A interlayer was prepared on copper by plasma cladding.Ni60A interlayer acted as a bridge to promote the element diffusion,thus achieving metallurgical bonding.Due to the strengthening effect ofγ-Co,Cr_(23)C_(6)and Cr_(7)C_(3)phases,the wear resistance of Co06–Ni60A coating was much higher than that of copper substrate.As the temperature increased,the wear resistance of coating decreased first and then increased.The coating exhibited better wear resistance at 600℃ due to the oxidation wear mechanism.Compared with copper substrate and Ni60A,the oxidation resistance of Co06 was increased by 6.0 and 1.9 times,respectively.For melting loss resistance,Co06–Ni60A coating was superior to Ni60A single-layer coating,but the molten iron can still form a micro-metallurgical bonding with the coating surface.展开更多
The high-temperature oxidation behaviors of the NiCrAIYSi/P-YSZ thermal barrier coatings （TBCs） produced by electron beam-physical vapor deposition （EB-PVD） on directionally solidified （DS） and single crystalli...The high-temperature oxidation behaviors of the NiCrAIYSi/P-YSZ thermal barrier coatings （TBCs） produced by electron beam-physical vapor deposition （EB-PVD） on directionally solidified （DS） and single crystalline （SC） Ni-based superalloy substrates were investigated. The cross-sectional microstructure investigation, isothermal and cyclic oxidation tests were conducted for the comparison of oxidation behaviors of TBCs on different substrates. Although TBC on DS substrate has a relatively higher oxidation rate, it has a longer thermal cycling lifetime than that on SC substrate. The primary factor for TBC spallation is the mismatch of thermal expansion coefficient （TEC） of the bond coat and substrate. The morphological feature of thermally grown oxide （TGO） has a strong influence on the TBC performance. By optimizing the elemental interdiffusion between bond coat and substrate, a high quality TGO layer is formed on the DS substrate, and therefore the TBC oxidation behavior is improved.展开更多
Chromium oxide ceramic materials are widely used in high-temperature applications requiring high wear resistance and lubricity.To further improve the friction and wear performance and high-temperature stability of chr...Chromium oxide ceramic materials are widely used in high-temperature applications requiring high wear resistance and lubricity.To further improve the friction and wear performance and high-temperature stability of chromium oxide thin films,this study attempted to dope rare earth(RE)element Y(yttrium)and deposited CrYO high-temperature self-lubricating ceramic thin films with different doping levels on the surface of IN718 alloys by using multi-arc ion plating technology.The deposited films were annealed at 1000℃for 2 h under atmospheric conditions to analyze the changes in phase composition and thickness,and the friction and wear characteristics of the CrYO films were tested using a high-temperature friction and wear tester in the temperature range of 25–600℃.The results show that the CrYO-2 film has a dense multilayer structure,and the multilayer oxide film produces interlayer sliding under frictional shear,thus providing lubrication.In particular,the friction coefficients are as low as about 0.25 in the middle and high-temperature sections(400,600℃),which provides good high-temperature tribological properties.In addition,the doping of Y elements dramatically affects the formation of the oxide layer and the distribution of voids in the film,changing the diffusion process of the elements of the base material inside the film and at the film-air interface at high temperatures.After two annealing treatments,the film thickness increased from 1.81 to 2.25μm,and the volume expansion of the films was effectively controlled compared with that of the Cr_(2)O_(3)films.展开更多
Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the...Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.展开更多
To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electric...To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electrical current and high-temperature exposure is investigated.Isothermal thermogravimetric analysis was employed to quantify oxidation kinetics,complemented by microstructural characterization using X-ray diffraction,scanning electron microscopy with energy-dispersive spectroscopy and transmission electron microscopy.Experimental results demonstrate that the applied current dramatically enhances oxidation rates,increasing specific mass gain from 0.25 mg/cm^(2)(0 A/cm^(2))to 5.20 mg/cm^(2)(0.2 A/cm^(2))and oxide scale thickness from 1.87 to 15.62μm after 200 h.This acceleration originates from current-induced electromigration forces that promote cationic transport through the oxide layer.The quantitative relationships between current density and oxidation parameters are established,enabling predictive modeling of interconnector degradation in solid oxide fuel cell(SOFC)systems.展开更多
The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coat...The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coating’s resistance to CMAS corrosion.The results indicate a phase transformation over time,transitioning from Ca_(2)Lu_(8)(SiO_(4))6O_(2) apatite and Lu_(2)Si_(2)O_(7) to solely Lu_(2)Si_(2)O_(7).The interaction of the Lu_(2)Si_(2)O_(7) coating with the CMAS melts was divided into three stages based on the corrosion reaction behavior.The delamination cracks were distributed throughout the interface between the Si bond layer and Lu_(2)Si_(2)O_(7) layer after corroded at 1400℃ for 50 h,signifying coating failure.In addition,the influence of monosilicates,disilicates,and corrosion duration on the recession layer thickness was analyzed by comparing previous reports on RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7) coatings(RE=Gd,Yb,Lu,Er).Furthermore,the variation in the thermally grown oxide layer thickness in CMAS-corroded Lu_(2)Si_(2)O_(7) coatings was systematically investigated.展开更多
In igneous-intruded coal seams,coal undergoes significant metamorphism,which critically alters its pore structure and oxygen consumption dynamics,thereby elevating its spontaneous combustion tendency.This study invest...In igneous-intruded coal seams,coal undergoes significant metamorphism,which critically alters its pore structure and oxygen consumption dynamics,thereby elevating its spontaneous combustion tendency.This study investigates the specific surface area,pore volume,structure complexity/connectivity,heterogeneity/local features of pore size distribution,and oxygen consumption dynamics of igneous metamorphic coal through N_(2)/CO_(2) isothermal adsorption tests and low-temperature oxidation experiments,and elucidates the influence mechanisms of pore structure evolution on oxygen consumption dynamics during low-temperature oxidation.With increasing metamorphic degree,igneous metamorphic coal exhibits a more pronounced reduction in specific surface area during oxidation,while the increase in structure complexity due to coal-oxygen reactions is suppressed.Thermally metamorphic coal demonstrates accelerated oxygen consumption,with oxidation amplifying the difference in reaction rates compared to raw coal.Key mechanisms include oxidation-induced reduction in mesopore complexity and micropore volume,decreased dominance of small-pore-volume apertures,and increased heterogeneity,collectively leading to a lower half-oxygen-consuming temperature and steeper oxygen consumption curves.Simultaneously,increased pore volume/complexity and reduced uniformity/connectivity act synergistically to enhance oxygen consumption capacity,highlighting the coupling between pore structure evolution and oxidation behavior in igneous metamorphic coal.This study provides theoretical insights into the pore-oxygen coupling mechanisms governing coal spontaneous combustion in igneous intrusion areas.展开更多
We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) change...We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 h.The typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable technique.To investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat test.Based on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation treatment.Further investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.展开更多
Two kinds of NiCrAlY coatings(Ni-25Cr-10Al-0.5Y)were prepared on K417 superalloy using ion plating(AIP)and magnetron sputtering(MS),respectively.The isothermal and cyclic oxidation behaviors of the two NiCrAlY coating...Two kinds of NiCrAlY coatings(Ni-25Cr-10Al-0.5Y)were prepared on K417 superalloy using ion plating(AIP)and magnetron sputtering(MS),respectively.The isothermal and cyclic oxidation behaviors of the two NiCrAlY coatings were evaluated at 1323 K in stair air.The results revealed that the nanocrystalline NiCrAlY coating exhibited better isothermal and cyclic oxidation resistance compared to the conventional NiCrAlY at 1323 K.The mass gain and parabolic rate constant Kp of the nanocrystalline NiCrAlY coating were 45.2%and 44.7%lower than those of the conventional NiCrAlY coating,respectively.During cyclic oxidation,the tendency for spallation of the oxide scale was evidently decreased by nanocrystallization due to the formation of a continuous,compact,adherent,and slow-growing exclusiveα-Al_(2)O_(3)scale.The mechanism responsible for the improvement of the nanocrystalline NiCrAlY coating was discussed.展开更多
The exploitation of organic-inorganic hybrid perovskites(OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumpti...The exploitation of organic-inorganic hybrid perovskites(OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumption and fast switching. However, the inherent thermal instability of perovskites limits the application of OIHPs-based resistive memories under extreme conditions, while the infiuence of thermal effects on their resistance change characteristics remains unclear. Herein, a novel 2D <100>-oriented high-temperature resistant OIHP [(BIZ-H)_(2)(PbBr_(4))]n(BIZ = benzimidazole) is prepared as an active layer material to fabricate FTO/[(BIZ-H)_(2)(PbBr_(4))]n/Ag resistive memory with excellent thermal reproducibility and stability up to 120℃. The increase in temperature leads to a decrease in the PbBr_(6) octahedral distortion in the crystal structure, an increase in hydrogen bonding between the(BIZ-H)+cation and the(PbBr_(4))_(n)^(2n-)layer, and a shortening of the spacing of the inorganic layers, which is found to result in the creation and predominance of thermally activated traps with increasing temperature. This work provides a new direction for the next generation of OIHPs-based resistive memories with high-temperature tolerance.展开更多
The oxidation behavior and mechanism of as-received and 30 % cold-rolled alumina-forming austenitic(AFA) steel were investigated in dry air at 700℃.The results show that the mass gain per unit area curves of as-recei...The oxidation behavior and mechanism of as-received and 30 % cold-rolled alumina-forming austenitic(AFA) steel were investigated in dry air at 700℃.The results show that the mass gain per unit area curves of as-received and 30 % cold-rolled steels subject to near-parabolic law before 100 h oxidation time.Two samples both show higher high-temperature oxidation resistance due to the formation of dense Al_(2)O_(3) oxide scale.Gradual spallation of outer scale results in the formation of continuous and dense alumina scale.Dislocations can act as short-circuit diffusion channel for the diffusion of Al from alloy matrix to surface,and also provide nucleation sites for B2-NiAl phase,which ensure the continuous formation of Al_(2)O_(3) scale.展开更多
基金supported by National Key Research and Development Program of China(Grant No.2022YFB3304800)the Reviving-Liaoning Excellence Plan(XLYC2203186).
文摘The high-temperature compressive deformation behavior of medium manganese steel using a four-roll reversible rolling mill is investigated,revealing the effects of different Mn contents on the thermal deformation behavior of oxidation products in the alloy.It is found that within the experimental temperature range,the higher the deformation temperature,the better the plasticity of the oxidation products.It was observed that increasing the Mn content refines the grains,enhances the deformation ability of the oxidation products,and improves the flatness of the interfaces.Since(Fe,Mn)O has a similar crystal structure to FeO,the addition of Mn refines the grains of(Fe,Mn)O,causing the deformation to be distributed across more grains under the same deformation amount,and thereby improving its plasticity.At the interface between Fe-Mn alloy oxidation products and the matrix,there exists a spinel-phase solid solution,which can deform together with the oxidation products and the matrix at high temperatures.It was found that with increasing the Mn content,the size and number of pores between the spinel phases increased.First-principles simulation calculations were used to verify this,showing that Mn promotes the generation of vacancies.The greater number of pores in the spinel phase can effectively relieve the compressive stress caused by rolling deformation,thereby improving the deformation capability of the oxidation products at the interface.
基金National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.
基金supported by the Key R&D Program of Shandong Province,China(No.2025CXGC 010412)the National Key Research and Development Program of China(No.2022YFB3709300)the National Natural Science Foundation of China(No.U21A2048).
文摘The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical properties,can significantly enhance the oxidation resistance of Mg alloys.Based on our previous study,we conclude that REs such as Gd,Y,and Ce enhance the oxidation resistance of Mg-RE alloys.This article comprehensively reviews recent research progress on high-temperature oxidation behavior and the potential mechanism in Mg-RE alloys.Based on the thermodynamic and kinetic analyses,the evolution of the complex oxide system formed during the high-temperature oxidation of Mg-RE alloys is first summarized.The diffusion behavior and concentration control mechanisms of REs during the oxidation process and how these mechanisms affect the sustained growth of the oxide film and antioxidant properties were elucidated.Moreover,the different structures of the oxide films were classified,and their properties were discussed.Finally,this paper introduces the applications of commonly used REs in Mg alloys and frontier research on their oxidation mechanisms.Based on the above review,we propose that future research perspectives can be explored in terms of expanding the experimental temperature range for oxidation tests,optimizing the chemical composition by adding trace REs to study their synergistic mechanism,revealing the underlying oxidation mechanism through advanced in situ microscopic characterization methods,and investigating the mechanical properties of oxide films using diverse approaches.
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
基金Supported by National Natural Science Foundation of China(Grant Nos.52075048,51675058,12232004)Hunan Provincial Excellent Youth Project of the Education Department(Grant No.21B0304)+2 种基金Natural Science Foundation of Hunan Province(Grant No.2023JJ30025)Science and Technology Innovation Program of Hunan Province(Grant No.2023RC1058)Scientific Research Innovation Project for Graduate Student of Changsha University of Science and Technology(Grant No.CLSJCX22096)。
文摘The high-temperature oxidation resistance of AISI 321 stainless steel used in solar thermal power heat exchangers determines its service life.In this study,aluminizing and subsequent laser shock peening(LSP)treatments were employed to improve the high-temperature oxidation resistance of AISI 321 stainless steel at 620°C.These two treatments decreased the oxidation rate of AISI 321 steel.Specifically,the optimal oxidation resistance was observed in aluminized steel before oxidation for 144 h owing to the increased entropy of the LSP-treated specimen.After 144 h,LSP-treated steel achieved the best oxidation resistance because of the formation of a protectiveα-Al2O3film.Moreover,the large amount of subgrain boundaries formed on the aluminized layer of the LSP-treated samples could act as short-circuit paths for the outward diffusion of Al,facilitating the rapid nucleation ofα-Al2O3.Meanwhile,the aluminized layer could isolate the contact between the oxidation environment and matrix,thereby decreasing the oxidation rate.Furthermore,the minimum oxidation parabolic constant was calculated for LSP-treated steel(6.45787×10^(-14)),which was 69.18%and 36.36%that of aluminized and 321 steel,respectively,during the entire oxidation process.Therefore,the combination of aluminizing and LSP treatments can improve the high-temperature oxidation resistance of 321 stainless steel,providing a new idea for its surface treatment to achieve a long service life at high temperatures.
基金Projects (50771009, 50731001 and 51071013) supported by the National Natural Science Foundations of China Project (2010CB631200) supported by the National Basic Research Program of China
文摘3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was investigated using impedance spectroscopy （IS） combined with scanning electron microscopy （SEM）, Raman spectroscopy and X-ray diffractometry （XRD）. Various electrical responses observed in the impedance spectra corresponding to GY-YSZ grains and grain boundaries were explained using circuit modeling. The change in the conduction mechanism of GY-YSZ was found to be related to the O^2- vacancy and lattice distortion due to the stabilizer diffusion during the oxidation. The results also suggested that the specific oxidation information about the GY-YSZ grains and grain boundaries should be acquired at a moderate measurement temperature, which was related to the resistance value in the impedance spectra. The resistance values of the GY-YSZ grains and grain boundaries should be measured at 200 ℃ and 300 ℃, respectively.
基金National Natural Science Foundation of China(52071126)Natural Science Foundation of Tianjin City,China(22JCQNJC01240)+2 种基金Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1009G)Special Funds for Science and Technology Innovation in Hebei(2022X19)Anhui Provincial Natural Science Foundation(2308085ME135)。
文摘Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.
基金National Natural Science Foundation of China(52376076)Open Fund of Material Corrosion and Protection Key Laboratory of Sichuan Province(2023CL13)Laiwu Vocational and Technical College Teachers Research Fund(2023jsky05)。
文摘Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose hardness is 65 HRC and flexural strength is 1450 MPa.The high-temperature oxidation mechanism of TiC-based cermets was investigated through an X-ray diffractometer and scanning electron microscope.The added elements Ni and Cr along with their solid solutions not only bond with the hard phase TiC to ensure the physical performance of the cermet,but also impede the internal diffusion during oxidation by forming a dense composite oxide layer,thereby enhancing the oxidation resistance.The TiC-NiCr cermet exhibits a dense protective oxide layer at 900℃ and can endure continuous oxidation for approximately 1000 h.A methodology for fabricating TiC-NiCr metal matrix composites is proposed,and their oxidation resistance is evaluated,providing a theoretical and practical basis for simultaneously enhancing the mechanical properties and oxidation resistance and reducing production costs.
基金National Natural Science Foundation of China(52161009)Innovation Project of Postgraduate Students in North Minzu University(YCX24104)。
文摘To improve the high-temperature oxidation resistance of TiAlNb9 alloy,a Cr-Al-Y co-deposition coating was prepared on the alloy surface by the pack cementation method.The microstructure of the coating was analyzed by scanning electron microscope,energy dispersive spectrometer,and X-ray diffractometer,and the high-temperature oxidation properties of the substrate and coating at 1273 K were compared and studied.The results show that the Cr-Al-Y coating is about 30μm in thickness,and it has a dense structure and good film-substrate bonding.The coating includes an outer layer composed of TiCr_(2),TiCr,Ti_(4)Cr,and(Ti,Nb)Cr_(4) phases as well as an inner layer composed of Ti_(2)Al,and Nb-richγ-TiAl interdiffusion zone.The TiAlNb9 substrate forms an oxide layer composed of TiO_(2) and Al_(2)O_(3) at 1273 K.Due to its loose and porous structure,TiO_(2) oxide film cannot effectively isolate the internal diffusion of element O,resulting in continuous oxidation damage to the substrate.The Cr-Al-Y co-deposition coating forms a dense Cr_(2)O_(3) and Al_(2)O_(3) oxide layer during oxidation,effectively preventing the internal diffusion of element O and significantly improving the high-temperature oxidation resistance of the substrate alloy.
基金supported by the University Synergy Innovation Program of Anhui Province(Grant Nos.GXXT-2023-025 and GXXT-2023-026)Natural Science Foundation of Anhui Province(Grant Nos.2008085ME149,2308085QE132 and 2308065ME171)Anhui University Scientific Research Project(Grant Nos.2022AH040247,2023AH051660,2023AH051670 and 2023AH051671).
文摘To improve the high-temperature service properties of coppery tuyere,Co06 coating with a Ni60A interlayer was prepared on copper by plasma cladding.Ni60A interlayer acted as a bridge to promote the element diffusion,thus achieving metallurgical bonding.Due to the strengthening effect ofγ-Co,Cr_(23)C_(6)and Cr_(7)C_(3)phases,the wear resistance of Co06–Ni60A coating was much higher than that of copper substrate.As the temperature increased,the wear resistance of coating decreased first and then increased.The coating exhibited better wear resistance at 600℃ due to the oxidation wear mechanism.Compared with copper substrate and Ni60A,the oxidation resistance of Co06 was increased by 6.0 and 1.9 times,respectively.For melting loss resistance,Co06–Ni60A coating was superior to Ni60A single-layer coating,but the molten iron can still form a micro-metallurgical bonding with the coating surface.
文摘The high-temperature oxidation behaviors of the NiCrAIYSi/P-YSZ thermal barrier coatings （TBCs） produced by electron beam-physical vapor deposition （EB-PVD） on directionally solidified （DS） and single crystalline （SC） Ni-based superalloy substrates were investigated. The cross-sectional microstructure investigation, isothermal and cyclic oxidation tests were conducted for the comparison of oxidation behaviors of TBCs on different substrates. Although TBC on DS substrate has a relatively higher oxidation rate, it has a longer thermal cycling lifetime than that on SC substrate. The primary factor for TBC spallation is the mismatch of thermal expansion coefficient （TEC） of the bond coat and substrate. The morphological feature of thermally grown oxide （TGO） has a strong influence on the TBC performance. By optimizing the elemental interdiffusion between bond coat and substrate, a high quality TGO layer is formed on the DS substrate, and therefore the TBC oxidation behavior is improved.
基金financial support of the National Natural Science Foundation of China(Nos.U2141210,51975561)the Fundamental Research Funds for the Central Universities(No.31920220160)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y202084)the Key Program of the Lanzhou Institute of Chemical Physics of Chinese Academy of Sciences(No.KJZLZD-3).
文摘Chromium oxide ceramic materials are widely used in high-temperature applications requiring high wear resistance and lubricity.To further improve the friction and wear performance and high-temperature stability of chromium oxide thin films,this study attempted to dope rare earth(RE)element Y(yttrium)and deposited CrYO high-temperature self-lubricating ceramic thin films with different doping levels on the surface of IN718 alloys by using multi-arc ion plating technology.The deposited films were annealed at 1000℃for 2 h under atmospheric conditions to analyze the changes in phase composition and thickness,and the friction and wear characteristics of the CrYO films were tested using a high-temperature friction and wear tester in the temperature range of 25–600℃.The results show that the CrYO-2 film has a dense multilayer structure,and the multilayer oxide film produces interlayer sliding under frictional shear,thus providing lubrication.In particular,the friction coefficients are as low as about 0.25 in the middle and high-temperature sections(400,600℃),which provides good high-temperature tribological properties.In addition,the doping of Y elements dramatically affects the formation of the oxide layer and the distribution of voids in the film,changing the diffusion process of the elements of the base material inside the film and at the film-air interface at high temperatures.After two annealing treatments,the film thickness increased from 1.81 to 2.25μm,and the volume expansion of the films was effectively controlled compared with that of the Cr_(2)O_(3)films.
基金Project(GC13A113)supported by the Technology Research and Development Program of Heilongjiang Provincial Science and Technology DepartmentProject(12511469)supported by Heilongjiang Provincial Science and Technology Department
文摘Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.
基金supported by Natural Science Foundation of Wuhan(2024040701010051)Natural Science Foundation of Hubei(2023AFB111)and National Natural Science Foundation of China(52401108).
文摘To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electrical current and high-temperature exposure is investigated.Isothermal thermogravimetric analysis was employed to quantify oxidation kinetics,complemented by microstructural characterization using X-ray diffraction,scanning electron microscopy with energy-dispersive spectroscopy and transmission electron microscopy.Experimental results demonstrate that the applied current dramatically enhances oxidation rates,increasing specific mass gain from 0.25 mg/cm^(2)(0 A/cm^(2))to 5.20 mg/cm^(2)(0.2 A/cm^(2))and oxide scale thickness from 1.87 to 15.62μm after 200 h.This acceleration originates from current-induced electromigration forces that promote cationic transport through the oxide layer.The quantitative relationships between current density and oxidation parameters are established,enabling predictive modeling of interconnector degradation in solid oxide fuel cell(SOFC)systems.
基金supported by the National Science and Technology Major Project of China(No.2017-VI-0020-0093).
文摘The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coating’s resistance to CMAS corrosion.The results indicate a phase transformation over time,transitioning from Ca_(2)Lu_(8)(SiO_(4))6O_(2) apatite and Lu_(2)Si_(2)O_(7) to solely Lu_(2)Si_(2)O_(7).The interaction of the Lu_(2)Si_(2)O_(7) coating with the CMAS melts was divided into three stages based on the corrosion reaction behavior.The delamination cracks were distributed throughout the interface between the Si bond layer and Lu_(2)Si_(2)O_(7) layer after corroded at 1400℃ for 50 h,signifying coating failure.In addition,the influence of monosilicates,disilicates,and corrosion duration on the recession layer thickness was analyzed by comparing previous reports on RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7) coatings(RE=Gd,Yb,Lu,Er).Furthermore,the variation in the thermally grown oxide layer thickness in CMAS-corroded Lu_(2)Si_(2)O_(7) coatings was systematically investigated.
基金supported by the National Natural Science Foundation of China(No.52374247)the Joint Funds of the National Natural Science Foundation of China(No.U24B2042).
文摘In igneous-intruded coal seams,coal undergoes significant metamorphism,which critically alters its pore structure and oxygen consumption dynamics,thereby elevating its spontaneous combustion tendency.This study investigates the specific surface area,pore volume,structure complexity/connectivity,heterogeneity/local features of pore size distribution,and oxygen consumption dynamics of igneous metamorphic coal through N_(2)/CO_(2) isothermal adsorption tests and low-temperature oxidation experiments,and elucidates the influence mechanisms of pore structure evolution on oxygen consumption dynamics during low-temperature oxidation.With increasing metamorphic degree,igneous metamorphic coal exhibits a more pronounced reduction in specific surface area during oxidation,while the increase in structure complexity due to coal-oxygen reactions is suppressed.Thermally metamorphic coal demonstrates accelerated oxygen consumption,with oxidation amplifying the difference in reaction rates compared to raw coal.Key mechanisms include oxidation-induced reduction in mesopore complexity and micropore volume,decreased dominance of small-pore-volume apertures,and increased heterogeneity,collectively leading to a lower half-oxygen-consuming temperature and steeper oxygen consumption curves.Simultaneously,increased pore volume/complexity and reduced uniformity/connectivity act synergistically to enhance oxygen consumption capacity,highlighting the coupling between pore structure evolution and oxidation behavior in igneous metamorphic coal.This study provides theoretical insights into the pore-oxygen coupling mechanisms governing coal spontaneous combustion in igneous intrusion areas.
基金Funded by Scientific and Technological Innovation Project of Carbon Emission Peak and Carbon Neutrality of Jiangsu Province(No.BE2022028-4)。
文摘We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 h.The typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable technique.To investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat test.Based on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation treatment.Further investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.
基金financially supported by the National Natural Science Foundation of China(No.52101075)China Postdoctoral Science Foundation(Nos.2021M700557,2022M723272)+1 种基金Postdoctoral Scienceof Chongqing Natural Science Foundation(Nos.cstc2021jcyj-bshX0053,cstc2021jcyj-bshX0039)Scientific Research Foundation of Chongqing University of Technology(No.2020ZDZ004)。
文摘Two kinds of NiCrAlY coatings(Ni-25Cr-10Al-0.5Y)were prepared on K417 superalloy using ion plating(AIP)and magnetron sputtering(MS),respectively.The isothermal and cyclic oxidation behaviors of the two NiCrAlY coatings were evaluated at 1323 K in stair air.The results revealed that the nanocrystalline NiCrAlY coating exhibited better isothermal and cyclic oxidation resistance compared to the conventional NiCrAlY at 1323 K.The mass gain and parabolic rate constant Kp of the nanocrystalline NiCrAlY coating were 45.2%and 44.7%lower than those of the conventional NiCrAlY coating,respectively.During cyclic oxidation,the tendency for spallation of the oxide scale was evidently decreased by nanocrystallization due to the formation of a continuous,compact,adherent,and slow-growing exclusiveα-Al_(2)O_(3)scale.The mechanism responsible for the improvement of the nanocrystalline NiCrAlY coating was discussed.
基金financially supported by the Ph.D. start-up funds of Jiangxi Science and Technology Normal University (Nos. 2023BSQD11, 2023BSQD13)Jiangxi Province Key Laboratory of Organic Functional Molecules (No. 2024SSY05141)。
文摘The exploitation of organic-inorganic hybrid perovskites(OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumption and fast switching. However, the inherent thermal instability of perovskites limits the application of OIHPs-based resistive memories under extreme conditions, while the infiuence of thermal effects on their resistance change characteristics remains unclear. Herein, a novel 2D <100>-oriented high-temperature resistant OIHP [(BIZ-H)_(2)(PbBr_(4))]n(BIZ = benzimidazole) is prepared as an active layer material to fabricate FTO/[(BIZ-H)_(2)(PbBr_(4))]n/Ag resistive memory with excellent thermal reproducibility and stability up to 120℃. The increase in temperature leads to a decrease in the PbBr_(6) octahedral distortion in the crystal structure, an increase in hydrogen bonding between the(BIZ-H)+cation and the(PbBr_(4))_(n)^(2n-)layer, and a shortening of the spacing of the inorganic layers, which is found to result in the creation and predominance of thermally activated traps with increasing temperature. This work provides a new direction for the next generation of OIHPs-based resistive memories with high-temperature tolerance.
基金financially supported by the National Natural Science Foundation of China and Shanghai Baosteel Group Company(No. U1960204)the National Natural Science Foundation of China(Nos. 51871042 and 51501034)the Fundamental Research Funds for the Central Universities (No. N2023026)。
文摘The oxidation behavior and mechanism of as-received and 30 % cold-rolled alumina-forming austenitic(AFA) steel were investigated in dry air at 700℃.The results show that the mass gain per unit area curves of as-received and 30 % cold-rolled steels subject to near-parabolic law before 100 h oxidation time.Two samples both show higher high-temperature oxidation resistance due to the formation of dense Al_(2)O_(3) oxide scale.Gradual spallation of outer scale results in the formation of continuous and dense alumina scale.Dislocations can act as short-circuit diffusion channel for the diffusion of Al from alloy matrix to surface,and also provide nucleation sites for B2-NiAl phase,which ensure the continuous formation of Al_(2)O_(3) scale.
