This study employs advanced electrochemical and surface characterization techniques to investigate the impact of electrochemical hydrogen charging on the corrosion behavior and surface film of the Ti-6Al-4V alloy.The ...This study employs advanced electrochemical and surface characterization techniques to investigate the impact of electrochemical hydrogen charging on the corrosion behavior and surface film of the Ti-6Al-4V alloy.The findings revealed the formation ofγ-TiH andδ-TiH_(2) hydrides in the alloy after hydrogen charging.Prolonging hydrogen charging resulted in more significant degradation of the alloy microstructure,leading to deteriorated protectiveness of the surface film.This trend was further confirmed by the electrochemical measurements,which showed that the corrosion resistance of the alloy progressively worsened as the hydrogen charging time was increased.Consequently,this work provides valuable insights into the mechanisms underlying the corrosion of Ti-6Al-4V alloy under hydrogen charging conditions.展开更多
To clarify the correlation of single-crystalline structure with corrosion performance in high-strength TiAl alloys, electrochemical and surface characterization was performed by comparing Ti–45Al–8Nb dual-phase sing...To clarify the correlation of single-crystalline structure with corrosion performance in high-strength TiAl alloys, electrochemical and surface characterization was performed by comparing Ti–45Al–8Nb dual-phase single crystals with their polycrystalline counterparts in NaCl solution. Polarization curves show a lower corrosion rate and a higher pitting potential of ~280 mV for the dual-phase single crystals. Electrochemical impedance spectroscopy and potentiostatic polarization plots revealed a higher impedance of the charge transfer through the compact passive film. Surface composition analysis indicated a compact film with more content of Nb, as twice as that in the film on the polycrystals.Our results reflect that the dual-phase Ti–45Al–8Nb single crystals possess a higher corrosion resistance in NaCl solution, compared with their polycrystalline counterpart, arising from a more homogeneous microstructure and composition distribution.展开更多
Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium allo...Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium alloys due to their high chemical reactivity.Herein,a one-step hydrothermal processing was developed using a stearic-acid-based precursor medium,which enables the hydrothermal conversion and the formation of low surface energy materials concurrently to produce the super-hydrophobic and corrosion-resistant coating.The multiscale microstructures with nanoscale stacks and microscale spheres on the surface,as well as the through-thickness stearates,lead to the super-hydrophobicity and excellent corrosion resistance of the obtained coating.展开更多
The hot deformation behaviours of 316LN-Mn austenitic stainless steel were investigated by uniaxial isothermal compression tests at different temperatures and strain rates.The microstructural evolutions were also stud...The hot deformation behaviours of 316LN-Mn austenitic stainless steel were investigated by uniaxial isothermal compression tests at different temperatures and strain rates.The microstructural evolutions were also studied using electron backscatter diffraction.The flow stress decreases with the increasing temperature and decreasing strain rate.A constitutive equation was established to characterize the relationship among the deformation parameters,and the deformation activation energy was calculated to be 497.92 k J/mol.Processing maps were constructed to describe the appropriate processing window,and the optimum processing parameters were determined at a temperature of 1107-1160℃ and a strain rate of 0.005-0.026 s^(-1).Experimental results showed that the main nucleation mechanism is discontinuous dynamic recrystallization(DDRX),followed by continuous dynamic recrystallization(CDRX).In addition,the formation of twin boundaries facilitated the nucleation of dynamic recrystallization.展开更多
The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was f...The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was found that the antagonism effect resulting in the passivation and depassivation of 304L SS had significant distinctions at different CE periods.The passive behavior was predominant during the incubation period of CE where the metastable pitting initiated at the surface of 304L SS.Over the rising period of CE,the 304L SS experienced a transition from passivation to depassivation,leading to the massive growth of metastable pitting and stable pitting.The depassivation of304L SS was found to be dominant at the stable period of CE where serious localized corrosion occurred.展开更多
MCrAlY(M=Ni and/or Co)overlay coating is widely used as a protective coating against high temperature oxidation and corrosion.However,due to its big difference in chemical composition with the underlying superalloy,el...MCrAlY(M=Ni and/or Co)overlay coating is widely used as a protective coating against high temperature oxidation and corrosion.However,due to its big difference in chemical composition with the underlying superalloy,elements interdiffusion occurs inevitably.One of the direct results is the formation of interdiffusion zone(IDZ)and secondary reaction zone(SRZ)with a high density of fine topological closed-packed phases(TCPs),weakening dramatically the mechanical properties of the alloy substrate.It is by now the main problem of modern high-temperature metallic coatings,but there are still hardly any reports studying the formation,growth and transformation of IDZ and SRZ in deep,as well as the precipitation of TCPs.In this work,a typical NiCrAlY coating is deposited by arc ion plating on a single-crystal superalloy N5.Elements interdiffusion between them and its relationship on microstructure were clarified.Cr rather than Al from the coating diffuses into the alloy at high temperatures and segregates immediately beneath their interface,contributing largely to the formation of IDZ.Simultaneously,diffusion of Ni from the deep alloy to IDZ leads to the formation and continuous expansion of SRZ.展开更多
By performing the immersion,hydrogen evolution and electrochemical corrosion testing in a 0.1 mol/L NaCl solution,the corrosion performance of differently oriented samples cut from an as-rolled Mg-8wt.%Li alloy plate ...By performing the immersion,hydrogen evolution and electrochemical corrosion testing in a 0.1 mol/L NaCl solution,the corrosion performance of differently oriented samples cut from an as-rolled Mg-8wt.%Li alloy plate has been investigated and compared.It demonstrated that obvious anisotropy in corrosion resistance existed between the sample surfaces with different orientations.Among them,the corrosion rate of"ND"(the normal direction)samples with their surfaces perpendicular to the normal direction of the plate was the highest.The corrosion rate of"TD"(the transverse direction)samples with their surfaces perpendicular to the transverse direction of the plate took the second place.For the"RD"(the rolling direction)samples with their surfaces perpendicular to the rolling direction of the plate,they had the lowest corrosion rate.For all the samples,their corrosion performance and the pitting severity were mainly ascribed to the crystallographic texture ofα-Mg matrix phases because the formed surface films onβ-Li phases could provide good protection to the substrate.For the"ND"and"TD"samples,the exposed surfaces were composed of{0002},{1010}and{1120}planes ofα-Mg phases and subsequently resulted in their severe corrosion attack due to the corrosion couples between basal and prism planes.Since the crystallographic planes of exposedα-Mg phases on the surfaces of"RD"samples were mainly{1010}and{1120}prism planes,the pitting severity was the weakest.展开更多
The effect of aging treatment on the microstructure and corrosion behavior of a Fe-18Cr-15Mn-0.66N high-nitrogen stainless steel(HNSS) in 3.5 wt.% Na Cl solution was investigated using a series of electrochemical test...The effect of aging treatment on the microstructure and corrosion behavior of a Fe-18Cr-15Mn-0.66N high-nitrogen stainless steel(HNSS) in 3.5 wt.% Na Cl solution was investigated using a series of electrochemical tests, scanning electronic microscopy(SEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS). The results showed that the aging treatment led to the precipitation of CrN particles along the grain boundaries and their morphologies changed from dispersive particles to continuous network as the aging time increased up to 60 min. Aging time had minor effects on the corrosion potential and corrosion current density, but resulted in the sharp decrease in the pitting corrosion potential.The passive film behaved as a n-type semiconductor, and the donor density of the passive film increased with the aging time. Meanwhile, the fraction of stable oxide(CrO) in the passive film decreased with the aging time. It demonstrates that the aging treatment deteriorated the protectiveness of the passive film, hence weakened the corrosion resistance of HNSS.展开更多
The effect of hydro gen charging on microstructural evolution and corrosion behavior of a Ti-4Al-2V-1Mo-1Fe alloy in a 3.5 wt.% NaCl solution was investigated.The results showed that the hydrogen charging induced the ...The effect of hydro gen charging on microstructural evolution and corrosion behavior of a Ti-4Al-2V-1Mo-1Fe alloy in a 3.5 wt.% NaCl solution was investigated.The results showed that the hydrogen charging induced the formation and growth of γ-TiH and δ-TiH_(2) phases,leading to the initiation and propagation of hydrogen-induced cracks.It was also found that hydrogen charging can change the passivity of this alloy and increase its pitting corrosion susceptibility.The main reason for these was attributed to the fo rmation of hydrides in α phase in the Ti-4Al-2V-1Mo-1Fe alloy,leading to the preferential dissolution of the α phase and thus the deterioration in the protective ability of passive film.展开更多
The microstructure of nickel-base alloy C-276 irradiated at 500℃ with 300 keV self-ions (Ni + ) to a peak displacement damage of 4.5 displacements per atom was investigated by transmission electron microscopy. Both b...The microstructure of nickel-base alloy C-276 irradiated at 500℃ with 300 keV self-ions (Ni + ) to a peak displacement damage of 4.5 displacements per atom was investigated by transmission electron microscopy. Both black spots and dislocation loops were observed. The black spots were identified as small dislocation loops, with a density of (8.2±0.2)×10 15 cm-3 and the average loop size of about 15 nm. An increase of dislocation loop density would lead to the increase of the hardness in C-276 alloy, and the increment in yield strength was estimated by the dispersed barrier-hardening model. In [110] orientation, Burgers vectors of the dislocation loops were determined, and it was found that they were predominantly (a/2)<110>. In contrast to other nickel-base alloys, no voids were observed in C-276 alloy after being irradiated at elevated temperatures.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.52001142,52005228,51801218,51911530211,51905110)Young Scientists Sponsorship Program by CAST(Grant No.2022QNRC001).
文摘This study employs advanced electrochemical and surface characterization techniques to investigate the impact of electrochemical hydrogen charging on the corrosion behavior and surface film of the Ti-6Al-4V alloy.The findings revealed the formation ofγ-TiH andδ-TiH_(2) hydrides in the alloy after hydrogen charging.Prolonging hydrogen charging resulted in more significant degradation of the alloy microstructure,leading to deteriorated protectiveness of the surface film.This trend was further confirmed by the electrochemical measurements,which showed that the corrosion resistance of the alloy progressively worsened as the hydrogen charging time was increased.Consequently,this work provides valuable insights into the mechanisms underlying the corrosion of Ti-6Al-4V alloy under hydrogen charging conditions.
基金financially supported by the CityU internal supports under “The Structural Material Development Funding” program (No. CityU 7004894)National Natural Science Foundation of China (Nos. 51901086 and 51731006)Natural Science Foundation of Jiangsu Province, China (Nos. BK20190977 and BK 20180984)。
文摘To clarify the correlation of single-crystalline structure with corrosion performance in high-strength TiAl alloys, electrochemical and surface characterization was performed by comparing Ti–45Al–8Nb dual-phase single crystals with their polycrystalline counterparts in NaCl solution. Polarization curves show a lower corrosion rate and a higher pitting potential of ~280 mV for the dual-phase single crystals. Electrochemical impedance spectroscopy and potentiostatic polarization plots revealed a higher impedance of the charge transfer through the compact passive film. Surface composition analysis indicated a compact film with more content of Nb, as twice as that in the film on the polycrystals.Our results reflect that the dual-phase Ti–45Al–8Nb single crystals possess a higher corrosion resistance in NaCl solution, compared with their polycrystalline counterpart, arising from a more homogeneous microstructure and composition distribution.
基金support from the Fundamental Research Funds for the Central Universities of Hohai university(B200202122)National Natural Science Foundation of China(51878246 and 51979099)+1 种基金the Natural Science Foundation of Jiangsu Province of China(BK20191303)Key Research and Development Project of Jiangsu Province of China(BE2017148).
文摘Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium alloys due to their high chemical reactivity.Herein,a one-step hydrothermal processing was developed using a stearic-acid-based precursor medium,which enables the hydrothermal conversion and the formation of low surface energy materials concurrently to produce the super-hydrophobic and corrosion-resistant coating.The multiscale microstructures with nanoscale stacks and microscale spheres on the surface,as well as the through-thickness stearates,lead to the super-hydrophobicity and excellent corrosion resistance of the obtained coating.
基金financial support of the National Natural Science Foundation of China(Nos.52101105 and 51975263)。
文摘The hot deformation behaviours of 316LN-Mn austenitic stainless steel were investigated by uniaxial isothermal compression tests at different temperatures and strain rates.The microstructural evolutions were also studied using electron backscatter diffraction.The flow stress decreases with the increasing temperature and decreasing strain rate.A constitutive equation was established to characterize the relationship among the deformation parameters,and the deformation activation energy was calculated to be 497.92 k J/mol.Processing maps were constructed to describe the appropriate processing window,and the optimum processing parameters were determined at a temperature of 1107-1160℃ and a strain rate of 0.005-0.026 s^(-1).Experimental results showed that the main nucleation mechanism is discontinuous dynamic recrystallization(DDRX),followed by continuous dynamic recrystallization(CDRX).In addition,the formation of twin boundaries facilitated the nucleation of dynamic recrystallization.
基金financially supported of the National Natural Science Foundation of China (Nos.52101105 and 51975263)。
文摘The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was found that the antagonism effect resulting in the passivation and depassivation of 304L SS had significant distinctions at different CE periods.The passive behavior was predominant during the incubation period of CE where the metastable pitting initiated at the surface of 304L SS.Over the rising period of CE,the 304L SS experienced a transition from passivation to depassivation,leading to the massive growth of metastable pitting and stable pitting.The depassivation of304L SS was found to be dominant at the stable period of CE where serious localized corrosion occurred.
基金the National Natural Science Foundation of China Nos.51671053 and 51801021the Ministry of Industry and Information Technology Project No.MJ-2017-J-99)。
文摘MCrAlY(M=Ni and/or Co)overlay coating is widely used as a protective coating against high temperature oxidation and corrosion.However,due to its big difference in chemical composition with the underlying superalloy,elements interdiffusion occurs inevitably.One of the direct results is the formation of interdiffusion zone(IDZ)and secondary reaction zone(SRZ)with a high density of fine topological closed-packed phases(TCPs),weakening dramatically the mechanical properties of the alloy substrate.It is by now the main problem of modern high-temperature metallic coatings,but there are still hardly any reports studying the formation,growth and transformation of IDZ and SRZ in deep,as well as the precipitation of TCPs.In this work,a typical NiCrAlY coating is deposited by arc ion plating on a single-crystal superalloy N5.Elements interdiffusion between them and its relationship on microstructure were clarified.Cr rather than Al from the coating diffuses into the alloy at high temperatures and segregates immediately beneath their interface,contributing largely to the formation of IDZ.Simultaneously,diffusion of Ni from the deep alloy to IDZ leads to the formation and continuous expansion of SRZ.
基金financially supported by the National Key Research and Development Program of China under Grant(Nos.2017YFB0702001 and 2016YFB0301105)the Strategic New Industry Development Special Foundation of Shenzhen(No.JCYJ20170306141749970)+5 种基金the National Natural Science Foundation of China Projects under Grant(Nos.51871211 and 51701129)the Doctor Startup Fund of Natural Science Foundation Program of Liaoning Province(No.2019-BS-200)the funds of International Joint Laboratory for Light Alloys,Liaoning BaiQianWan Talents Programthe Domain Foundation of Equipment Advance Research of 13th Five-year Plan(No.61409220118)the Innovation Fund of Institute of Metal Research(IMR),Chinese Academy of Sciences(CAS)the National Basic Research Program of China(“973 Program”)(No.2013CB632205)。
文摘By performing the immersion,hydrogen evolution and electrochemical corrosion testing in a 0.1 mol/L NaCl solution,the corrosion performance of differently oriented samples cut from an as-rolled Mg-8wt.%Li alloy plate has been investigated and compared.It demonstrated that obvious anisotropy in corrosion resistance existed between the sample surfaces with different orientations.Among them,the corrosion rate of"ND"(the normal direction)samples with their surfaces perpendicular to the normal direction of the plate was the highest.The corrosion rate of"TD"(the transverse direction)samples with their surfaces perpendicular to the transverse direction of the plate took the second place.For the"RD"(the rolling direction)samples with their surfaces perpendicular to the rolling direction of the plate,they had the lowest corrosion rate.For all the samples,their corrosion performance and the pitting severity were mainly ascribed to the crystallographic texture ofα-Mg matrix phases because the formed surface films onβ-Li phases could provide good protection to the substrate.For the"ND"and"TD"samples,the exposed surfaces were composed of{0002},{1010}and{1120}planes ofα-Mg phases and subsequently resulted in their severe corrosion attack due to the corrosion couples between basal and prism planes.Since the crystallographic planes of exposedα-Mg phases on the surfaces of"RD"samples were mainly{1010}and{1120}prism planes,the pitting severity was the weakest.
基金financially supported by the National Natural Science Foundation of China (Nos. 52001142, 52005228, 51801218, 51911530211, and 51905110)Science Foundation of Jiangsu Province (No. BK 20180984)。
文摘The effect of aging treatment on the microstructure and corrosion behavior of a Fe-18Cr-15Mn-0.66N high-nitrogen stainless steel(HNSS) in 3.5 wt.% Na Cl solution was investigated using a series of electrochemical tests, scanning electronic microscopy(SEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS). The results showed that the aging treatment led to the precipitation of CrN particles along the grain boundaries and their morphologies changed from dispersive particles to continuous network as the aging time increased up to 60 min. Aging time had minor effects on the corrosion potential and corrosion current density, but resulted in the sharp decrease in the pitting corrosion potential.The passive film behaved as a n-type semiconductor, and the donor density of the passive film increased with the aging time. Meanwhile, the fraction of stable oxide(CrO) in the passive film decreased with the aging time. It demonstrates that the aging treatment deteriorated the protectiveness of the passive film, hence weakened the corrosion resistance of HNSS.
基金financially supported by the National Natural Science Foundation of China(Nos.51871211,51871225 and 51701129)。
文摘The effect of hydro gen charging on microstructural evolution and corrosion behavior of a Ti-4Al-2V-1Mo-1Fe alloy in a 3.5 wt.% NaCl solution was investigated.The results showed that the hydrogen charging induced the formation and growth of γ-TiH and δ-TiH_(2) phases,leading to the initiation and propagation of hydrogen-induced cracks.It was also found that hydrogen charging can change the passivity of this alloy and increase its pitting corrosion susceptibility.The main reason for these was attributed to the fo rmation of hydrides in α phase in the Ti-4Al-2V-1Mo-1Fe alloy,leading to the preferential dissolution of the α phase and thus the deterioration in the protective ability of passive film.
基金supported by the National Basic Research Program of China(No.2007CB2009800)the National Natural Science Foundation of China(Nos.11075119and11275140)+1 种基金the Fundamental Research Funds for the Central Universities(No.20102020201000013)the National Magnetic Confinement Fusion Program(No.2011GB108009)
文摘The microstructure of nickel-base alloy C-276 irradiated at 500℃ with 300 keV self-ions (Ni + ) to a peak displacement damage of 4.5 displacements per atom was investigated by transmission electron microscopy. Both black spots and dislocation loops were observed. The black spots were identified as small dislocation loops, with a density of (8.2±0.2)×10 15 cm-3 and the average loop size of about 15 nm. An increase of dislocation loop density would lead to the increase of the hardness in C-276 alloy, and the increment in yield strength was estimated by the dispersed barrier-hardening model. In [110] orientation, Burgers vectors of the dislocation loops were determined, and it was found that they were predominantly (a/2)<110>. In contrast to other nickel-base alloys, no voids were observed in C-276 alloy after being irradiated at elevated temperatures.