Traceability precept is a broadcast encryption technique that content suppliers can trace malicious authorized users who leak the decryption key to an unauthorized user. To protect the data from eavesdropping, the con...Traceability precept is a broadcast encryption technique that content suppliers can trace malicious authorized users who leak the decryption key to an unauthorized user. To protect the data from eavesdropping, the content supplier encrypts the data and broadcast the cryptograph that only its subscribers can decrypt. However, a traitor may clone his decoder and sell the pirate decoders for profits. The traitor can modify the private key and the decryption program inside the pirate decoder to avoid divulging his identity. Furthermore, some traitors may fabricate a new legal private key together that cannot be traced to the creators. So in this paper, a renewed precept is proposed to achieve both revocation at a different level of capacity in each distribution and black-box tracing against self-protective pirate decoders. The rigorous mathematical deduction shows that our algorithm possess security property.展开更多
Heat-resistant alloys with excellent mechanical properties are widely used in various fields,and further improvement in their properties is essential to meet the requirements in new-generation advanced supercritical b...Heat-resistant alloys with excellent mechanical properties are widely used in various fields,and further improvement in their properties is essential to meet the requirements in new-generation advanced supercritical boilers,nuclear reactors,superheaters,and other new materials applications.To effectively enhance the comprehensive performance of heat-resistant alloys,second-phase particle strengthening has been widely studied,and in the face of different service envi-ronments of advanced heat-resistant steels,the selection of suitable second-phase particles is essential to maximize the performance of these alloys.To this end,three major types of reinforcing phases in heat-resistant alloys such as carbides,rare earth oxides,and intermetallic compounds are summarized.A comparative analysis of the precipitation behavior of the reinforcing phases with different types as well as the risks and means of controlling their use in service,is presented.Key parameters for the application of various types of second-phase particles in heat-resistant alloys are provided to support the design and preparation of new ultrahigh-performance heat-resistant alloys.展开更多
Objective: Acupuncture has a definite therapeutic effect on chronic obstructive pulmonary disease (COPD), and the cholinergic anti-inflammatory pathway (CAP) has been shown to be involved in regula- tion of infla...Objective: Acupuncture has a definite therapeutic effect on chronic obstructive pulmonary disease (COPD), and the cholinergic anti-inflammatory pathway (CAP) has been shown to be involved in regula- tion of inflammation. In this study, we investigated whether electro-acupuncture (EA) affects the CAP in COPD,Methods: Sprague-Dawley rats were induced into COPD through exposure to cigarette smoke combined with lipopolysaccharide. EA treatment was applied at Zusanli (ST36) and Feishu (BL13) points for 30 min/d for 7 d. Seventy-two rats were randomly divided into six study groups, including normal, normal + EA, normal + α-bungarotoxin (α-BGT) (the antagonist of the nicotinic acetylcholine receptor α7 subunit (α7nAChR)) + EA, COPD, COPD + EA, and COPD + α-BGT + EA. Lung function, pathology and vagus nerve discharge were tested. The levels of acetylcholine (ACh), acetylcholinesterase (ACHE), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-ct) in bronchoalveolar lavage fluid (BALF) and lung tissue were measured by enzyme-linked immunosorbent assay. The mRNA and protein expression and immunoreac- tivity of α7nAChR and its postreceptor inflammation signal pathway, including janus kinase 2 (JAK2), sig- nal transducers and activators of transcription 3 (STAT3), nuclear factor-KB (NF-KB), were observed by quantitative reverse transcription-polymerase chain reaction, Western blot and immunohistochemistry. Results: Compared with normal rats, there were a significant decline in lung function and discharge of the vagus nerve (P 〈 0.01), a marked sign of lung inflammation and an increase of ACh, ACHE, IL-6 and TNF-α level in BALF or lung tissue (P 〈 0.05, P 〈 0.01 ) and higher expression of 0t7nAChR, JAK2, STAT3 and NF-αB (P 〈 0.05, P 〈 0.01) in the COPD rats. In rats receiving EA, the lung function and vagal discharge were enhanced (P 〈 0.01 ), lung inflammation was improved and the levels of ACh, ACHE, IL-6 and TNF-α were decreased (P 〈 0.01). Further, the expression of α7nAChR, JAK2, STAT3 and NF-κB was downregulated (P 〈 0.05, P 〈 0.01 ). However, the above effects of EA were blocked in rats injected with α-BCT (P 〈 0.01 ). Conclusion: EA treatment can reduce the lung inflammatory response and improve lung function in COPD, which may be related to its involvement in the regulation of CAP.展开更多
Inflammation and lung function decline are the main pathophysiological features of chronic obstructive pulmonary disease (COPD). Acupuncture can improve lung function in patients with COPD, but the underlying mechan...Inflammation and lung function decline are the main pathophysiological features of chronic obstructive pulmonary disease (COPD). Acupuncture can improve lung function in patients with COPD, but the underlying mechanisms are not well understood. Orexins (OXs), which are found in peripheral plasma, are neuropeptides that regulate respiration and their levels are related to COPD. Therefore, we hypothesized that acupuncture might alter OXs, reduce lung inflammation and improve lung function in COPD. METHODS: COPD was induced in rats by exposure to cigarette smoke for 8 weeks and injecting with lipopolysaccharide twice. Electroacupuncture (EA) was performed at Feishu (BL13) and Zusanli (ST36) for 30 min/d for 2 weeks. Rat lung function and morphology were assessed after EA. The levels of tumor necrosis factor-α (TNF-a) and intedeukin-1β (IL-16) in bronchoalveolar lavage fluid (BALF) and orexin A and B levels in the lung tissue were detected by enzyme-linked immunosorbent assay. OX receptor mRNA levels and immunopositive cells were assessed with real-time polymerase chain reaction and immunohistochemical methods, respectively. The relationships among lung function, cell factors, and OX levels were analyzed by Pearson correlation analyses. RESULTS: Compared with the control group, lung function was significantly decreased in the rats with COPD (P〈0.05). There were obvious increases in TNF-α and IL-1β levels in BALF (P〈0.05 and P〈0.01, respectively), orexin A level in lung tissue (P〈0.01; but not orexin B) and mRNA expressions of OX 1 type receptor (OXR1) and OX 2 type receptor (OXR2) in lung tissue (P〈0.05 and P〈0.01, respectively); the integrative optical densities (IODs) of both receptors were greater in the COPD group (P〈0.05). For rats with COPD subjected to EA, lung function was improved (P〈0.05). There were notable decreases in TNF-a and IL-1β levels (P〈0.05 and 〈0.01, respectively) in BALF. Orexin A, but not orexin B, levels in lung tissue also decreased (P〈0.01), as did mRNA expression of OXlR and OX2R in lung tissue (P〈0.05 and P〈0.01, respectively). Receptor IODs were also reduced after EA treatment (P〈0.05). Furthermore, orexin A levels and ratio of forced expiratory volume in 0.3 s to forced vital capacity were strongly negatively correlated (P〈0.01), and orexin A was positively correlated with TNF-α and IL-1β (P〈0.001 and P〈0.05, respectively).CONCLUSION: EA at Zusanli and Feishu improved lung function of rats with COPD and had an anti-inflammatory effect, which may be related to down-regulation of OXA and its receptors.展开更多
Pulsed external field, including electric, magnetic, ultrasonic and laser, as aninstantaneous high energy input method with high efficiency and low energyconsumption, have long been known to can modify the microstruct...Pulsed external field, including electric, magnetic, ultrasonic and laser, as aninstantaneous high energy input method with high efficiency and low energyconsumption, have long been known to can modify the microstructure and propertiesof materials. This includes electroplasticity, magnetoplasticity, phase transformations,recrystallization, grain refinement, texture control, inclusion removal.展开更多
The effect of Al8Cu4Er phase on the corrosion behavior of Al-Cu-Mg alloy with rare earth Er addition in an under-aging state was studied.The results revealed that the addition Er into the Al-Cu-Mg alloy induced the fo...The effect of Al8Cu4Er phase on the corrosion behavior of Al-Cu-Mg alloy with rare earth Er addition in an under-aging state was studied.The results revealed that the addition Er into the Al-Cu-Mg alloy induced the formation of Al8Cu4 Er phase.The Al8Cu4Er phase can significantly refine the grains during recrystallization,thereby suppressing the continuous precipitation of S-phase at grain boundaries and improving the resistance to intergranular corrosion.Conversely,the corrosion susceptibility of local regions around the Al8Cu4Er phase with large dimension was higher than that of the AlCuFeMnSi phase,but weaker than that of θ phase,resulting in decreased pitting corrosion resistance.展开更多
Circadian clock genes in peripheral tissues usually play an important role in regulating the circadian rhythms. Light is the most important environmental signal for synchronizing endogenous rhythms with the daily ligh...Circadian clock genes in peripheral tissues usually play an important role in regulating the circadian rhythms. Light is the most important environmental signal for synchronizing endogenous rhythms with the daily light-dark cycle, and compound eyes are known as the principal circadian photoreceptor for photic entrainment in most moths. However, there is little evidence for circadian timing in compound eyes. In the current study, we isolated the timeless gene, designated Ha-tim (GenBank accession number: KM233162), from the cotton bo 11 worm Helicoverpa armigera. Ha-tim and period (Haper) showed low messenger RNA levels in the compound eyes compared to the other tested adult organs. Ha-tim and Ha-per transcript levels were dependent on an endogenous rhythm that fluctuated over a daily cycle in the compound eyes and heads. The cycles of Hatim and Ha-per transcript levels followed similar time courses, and identical expression patterns of the two genes were observed in the compound eyes and heads. Ha-tim and Ha-per were dowregulated in the compound eyes after light exposure, copulation and starvation. These results indicated that Ha-tim and Ha-per transcript levels were regulated by endogenous and exogenous factors. Our study helped to improve our understanding of the circadian clock machinery in compound eyes and other peripheral tissues.展开更多
As the condensed matter analog of Majorana fermion, the Majorana zero-mode is well known as a building block of fault-tolerant topological quantum computing. This review focuses on the recent progress of Majorana expe...As the condensed matter analog of Majorana fermion, the Majorana zero-mode is well known as a building block of fault-tolerant topological quantum computing. This review focuses on the recent progress of Majorana experiments, especially experiments about semiconductor-superconductor hybrid devices. We first sketch Majorana zero-mode formation from a bottom-up view,which is more suitable for beginners and experimentalists. Then, we survey the status of zero-energy state signatures reported recently, from zero-energy conductance peaks, the oscillations, the quantization, and the interactions with extra degrees of freedom. We also give prospects of future experiments for advancing one-dimensional semiconductor nanowire-superconductor hybrid materials and devices.展开更多
The fracture of pipelines caused by corrosion cracks and the resulting oil and gas leakage can lead to great environmentalpollution and economic losses. These negative effects are due to serious corrosion of the plain...The fracture of pipelines caused by corrosion cracks and the resulting oil and gas leakage can lead to great environmentalpollution and economic losses. These negative effects are due to serious corrosion of the plain carbon steels used for armorof flexible pipe in oil and gas transmission medium. However, corrosion resistance of carbon steel armors has yet to beimproved. In this study, the relationship between corrosion resistance and pearlite fraction in the plain carbon steels hasbeen investigated through the application of pulsed electric current. Based on immersion test and electrochemical mea-surement, pulsed electric current increases the corrosion resistance of the plain carbon steels by reducing the fraction ofpearlite phase. Pitting corrosion, which tends to initiate by galvanic corrosion of ferrite and cementite, is therefore inhibiteddue to the decrease in pearlite fraction (mixture of ferrite and cementite) under electropulsing.展开更多
In this study,high density electric current pulse(ECP)treatment was introduced instead of the conventional solution treatment,and theγ′phase was completely dissolved under the ECP treatment within only several milli...In this study,high density electric current pulse(ECP)treatment was introduced instead of the conventional solution treatment,and theγ′phase was completely dissolved under the ECP treatment within only several milliseconds at 1148°C.Due to the extremely short treatment time and high cooling rate,the growth ofγ-phase matrix grain andγ′phase precipitate was effectively retarded.By comparing with the conventional heat process,the grain size of ECP treated sample was controlled to about 15μm,the size of the re-precipitatedγ′phase reduced from 65 to 35 nm,and the number density ofγ′precipitate increased from 1.46×108 to 3.03×108/mm2.The Vickers hardness,ultimate tensile strength and yield strength of the ECP treated sample were significantly improved.According to the theoretical derivation of kinetics,the ECP treatment introduces an extra electrical free energy which promoted the dissolution ofγ′phase.The ECP treatment may provide a new method for solution treatment of the Ni-based superalloy.展开更多
Controlling the precipitation through thermomechanical treatment is an important method to improve the corrosion resistance of Al–Cu–Mg alloys. In this study, the corrosion behaviors of Al–Cu–Mg alloys in the solu...Controlling the precipitation through thermomechanical treatment is an important method to improve the corrosion resistance of Al–Cu–Mg alloys. In this study, the corrosion behaviors of Al–Cu–Mg alloys in the solution-treated state and retrogressiontreated state under cold rolling deformation and then natural aging were investigated. In the solution-treated series alloys, the cold-rolled deformation improved the resistance to intergranular corrosion by suppressing the precipitation of the S-phase on the grain boundaries. The increased pitting potential and corrosion potential were related to the increased concentration of solute atoms within the grain interiors and the eliminated S-phase on grain boundaries. In the retrogression-treated series alloys, the 30% cold rolling deformation stimulated the growth of the S-phase and transformed the S-phase distribution from discontinuous to continuous on the grain boundaries, thereby changing the pitting corrosion to the network corrosion morphology. The precipitation of the S-phase with large dimension within the grain interiors contributed to the decreased pitting potential and corrosion potential.展开更多
基金This work was supported by the Large-Scale Security SoC Project of Wuhan Science and Technology Bureau of China under Grand No. 20061005119.
文摘Traceability precept is a broadcast encryption technique that content suppliers can trace malicious authorized users who leak the decryption key to an unauthorized user. To protect the data from eavesdropping, the content supplier encrypts the data and broadcast the cryptograph that only its subscribers can decrypt. However, a traitor may clone his decoder and sell the pirate decoders for profits. The traitor can modify the private key and the decryption program inside the pirate decoder to avoid divulging his identity. Furthermore, some traitors may fabricate a new legal private key together that cannot be traced to the creators. So in this paper, a renewed precept is proposed to achieve both revocation at a different level of capacity in each distribution and black-box tracing against self-protective pirate decoders. The rigorous mathematical deduction shows that our algorithm possess security property.
基金The authors express their gratitude to the National Science Foundation for Young Scientists of China(51704021)Key Research and Development Projects of Shandong Province(2021CXGC010)+1 种基金Key Research and Development Projects of Sichuan Province(021YFG0114)Fundamental Research Funds for the Central Universities(FRF-IDRY-20-015,FRF-TP-20-004A3,FRF-TP-19-030A2,and FRF-TP-16-079A1)for their kind financial support.
文摘Heat-resistant alloys with excellent mechanical properties are widely used in various fields,and further improvement in their properties is essential to meet the requirements in new-generation advanced supercritical boilers,nuclear reactors,superheaters,and other new materials applications.To effectively enhance the comprehensive performance of heat-resistant alloys,second-phase particle strengthening has been widely studied,and in the face of different service envi-ronments of advanced heat-resistant steels,the selection of suitable second-phase particles is essential to maximize the performance of these alloys.To this end,three major types of reinforcing phases in heat-resistant alloys such as carbides,rare earth oxides,and intermetallic compounds are summarized.A comparative analysis of the precipitation behavior of the reinforcing phases with different types as well as the risks and means of controlling their use in service,is presented.Key parameters for the application of various types of second-phase particles in heat-resistant alloys are provided to support the design and preparation of new ultrahigh-performance heat-resistant alloys.
基金supported by grants from the National Natural Science Foundation of China(No. 81373743)Outstanding Young Talents Support Program of Anhui(No. 20140181)
文摘Objective: Acupuncture has a definite therapeutic effect on chronic obstructive pulmonary disease (COPD), and the cholinergic anti-inflammatory pathway (CAP) has been shown to be involved in regula- tion of inflammation. In this study, we investigated whether electro-acupuncture (EA) affects the CAP in COPD,Methods: Sprague-Dawley rats were induced into COPD through exposure to cigarette smoke combined with lipopolysaccharide. EA treatment was applied at Zusanli (ST36) and Feishu (BL13) points for 30 min/d for 7 d. Seventy-two rats were randomly divided into six study groups, including normal, normal + EA, normal + α-bungarotoxin (α-BGT) (the antagonist of the nicotinic acetylcholine receptor α7 subunit (α7nAChR)) + EA, COPD, COPD + EA, and COPD + α-BGT + EA. Lung function, pathology and vagus nerve discharge were tested. The levels of acetylcholine (ACh), acetylcholinesterase (ACHE), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-ct) in bronchoalveolar lavage fluid (BALF) and lung tissue were measured by enzyme-linked immunosorbent assay. The mRNA and protein expression and immunoreac- tivity of α7nAChR and its postreceptor inflammation signal pathway, including janus kinase 2 (JAK2), sig- nal transducers and activators of transcription 3 (STAT3), nuclear factor-KB (NF-KB), were observed by quantitative reverse transcription-polymerase chain reaction, Western blot and immunohistochemistry. Results: Compared with normal rats, there were a significant decline in lung function and discharge of the vagus nerve (P 〈 0.01), a marked sign of lung inflammation and an increase of ACh, ACHE, IL-6 and TNF-α level in BALF or lung tissue (P 〈 0.05, P 〈 0.01 ) and higher expression of 0t7nAChR, JAK2, STAT3 and NF-αB (P 〈 0.05, P 〈 0.01) in the COPD rats. In rats receiving EA, the lung function and vagal discharge were enhanced (P 〈 0.01 ), lung inflammation was improved and the levels of ACh, ACHE, IL-6 and TNF-α were decreased (P 〈 0.01). Further, the expression of α7nAChR, JAK2, STAT3 and NF-κB was downregulated (P 〈 0.05, P 〈 0.01 ). However, the above effects of EA were blocked in rats injected with α-BCT (P 〈 0.01 ). Conclusion: EA treatment can reduce the lung inflammatory response and improve lung function in COPD, which may be related to its involvement in the regulation of CAP.
基金supported by grants from the National Natural Science Foundation of China(No.81072870No.81102660+1 种基金No.81373743)Open Research Fund of Zhejiang First-foremost Key Subject-Acupuncture&Moxibustion(No.ZTK2010B06)
文摘Inflammation and lung function decline are the main pathophysiological features of chronic obstructive pulmonary disease (COPD). Acupuncture can improve lung function in patients with COPD, but the underlying mechanisms are not well understood. Orexins (OXs), which are found in peripheral plasma, are neuropeptides that regulate respiration and their levels are related to COPD. Therefore, we hypothesized that acupuncture might alter OXs, reduce lung inflammation and improve lung function in COPD. METHODS: COPD was induced in rats by exposure to cigarette smoke for 8 weeks and injecting with lipopolysaccharide twice. Electroacupuncture (EA) was performed at Feishu (BL13) and Zusanli (ST36) for 30 min/d for 2 weeks. Rat lung function and morphology were assessed after EA. The levels of tumor necrosis factor-α (TNF-a) and intedeukin-1β (IL-16) in bronchoalveolar lavage fluid (BALF) and orexin A and B levels in the lung tissue were detected by enzyme-linked immunosorbent assay. OX receptor mRNA levels and immunopositive cells were assessed with real-time polymerase chain reaction and immunohistochemical methods, respectively. The relationships among lung function, cell factors, and OX levels were analyzed by Pearson correlation analyses. RESULTS: Compared with the control group, lung function was significantly decreased in the rats with COPD (P〈0.05). There were obvious increases in TNF-α and IL-1β levels in BALF (P〈0.05 and P〈0.01, respectively), orexin A level in lung tissue (P〈0.01; but not orexin B) and mRNA expressions of OX 1 type receptor (OXR1) and OX 2 type receptor (OXR2) in lung tissue (P〈0.05 and P〈0.01, respectively); the integrative optical densities (IODs) of both receptors were greater in the COPD group (P〈0.05). For rats with COPD subjected to EA, lung function was improved (P〈0.05). There were notable decreases in TNF-a and IL-1β levels (P〈0.05 and 〈0.01, respectively) in BALF. Orexin A, but not orexin B, levels in lung tissue also decreased (P〈0.01), as did mRNA expression of OXlR and OX2R in lung tissue (P〈0.05 and P〈0.01, respectively). Receptor IODs were also reduced after EA treatment (P〈0.05). Furthermore, orexin A levels and ratio of forced expiratory volume in 0.3 s to forced vital capacity were strongly negatively correlated (P〈0.01), and orexin A was positively correlated with TNF-α and IL-1β (P〈0.001 and P〈0.05, respectively).CONCLUSION: EA at Zusanli and Feishu improved lung function of rats with COPD and had an anti-inflammatory effect, which may be related to down-regulation of OXA and its receptors.
文摘Pulsed external field, including electric, magnetic, ultrasonic and laser, as aninstantaneous high energy input method with high efficiency and low energyconsumption, have long been known to can modify the microstructure and propertiesof materials. This includes electroplasticity, magnetoplasticity, phase transformations,recrystallization, grain refinement, texture control, inclusion removal.
基金financially supported by the National Natural Science Foundation of China(Nos.51874023,51601011 and U1860206)the Fundamental Research Funds for the Central Universities,Recruitment Program of Global Experts+1 种基金the State Grid ScientificTechnological Research Program of China(No.5211DS17001X)。
文摘The effect of Al8Cu4Er phase on the corrosion behavior of Al-Cu-Mg alloy with rare earth Er addition in an under-aging state was studied.The results revealed that the addition Er into the Al-Cu-Mg alloy induced the formation of Al8Cu4 Er phase.The Al8Cu4Er phase can significantly refine the grains during recrystallization,thereby suppressing the continuous precipitation of S-phase at grain boundaries and improving the resistance to intergranular corrosion.Conversely,the corrosion susceptibility of local regions around the Al8Cu4Er phase with large dimension was higher than that of the AlCuFeMnSi phase,but weaker than that of θ phase,resulting in decreased pitting corrosion resistance.
文摘Circadian clock genes in peripheral tissues usually play an important role in regulating the circadian rhythms. Light is the most important environmental signal for synchronizing endogenous rhythms with the daily light-dark cycle, and compound eyes are known as the principal circadian photoreceptor for photic entrainment in most moths. However, there is little evidence for circadian timing in compound eyes. In the current study, we isolated the timeless gene, designated Ha-tim (GenBank accession number: KM233162), from the cotton bo 11 worm Helicoverpa armigera. Ha-tim and period (Haper) showed low messenger RNA levels in the compound eyes compared to the other tested adult organs. Ha-tim and Ha-per transcript levels were dependent on an endogenous rhythm that fluctuated over a daily cycle in the compound eyes and heads. The cycles of Hatim and Ha-per transcript levels followed similar time courses, and identical expression patterns of the two genes were observed in the compound eyes and heads. Ha-tim and Ha-per were dowregulated in the compound eyes after light exposure, copulation and starvation. These results indicated that Ha-tim and Ha-per transcript levels were regulated by endogenous and exogenous factors. Our study helped to improve our understanding of the circadian clock machinery in compound eyes and other peripheral tissues.
基金supported by the National Natural Science Foundation of China (Grant No. 11904399)the Open Research Fund from State Key Laboratory of High Performance Computing of China (Grant No. 201901-09)。
文摘As the condensed matter analog of Majorana fermion, the Majorana zero-mode is well known as a building block of fault-tolerant topological quantum computing. This review focuses on the recent progress of Majorana experiments, especially experiments about semiconductor-superconductor hybrid devices. We first sketch Majorana zero-mode formation from a bottom-up view,which is more suitable for beginners and experimentalists. Then, we survey the status of zero-energy state signatures reported recently, from zero-energy conductance peaks, the oscillations, the quantization, and the interactions with extra degrees of freedom. We also give prospects of future experiments for advancing one-dimensional semiconductor nanowire-superconductor hybrid materials and devices.
基金financially supported by the National Natural Science Foundation of China(No.51601011)the Fundamental Research Funds for the Central Universities+2 种基金the Recruitment Program of Global Expertsthe State Grid Scientific and Technological Research Program of China(No.5211DS17001X)the Zhejiang Electric Power Corporation Scientific and Technological Research Program of China(No.5211DS5002 M).
文摘The fracture of pipelines caused by corrosion cracks and the resulting oil and gas leakage can lead to great environmentalpollution and economic losses. These negative effects are due to serious corrosion of the plain carbon steels used for armorof flexible pipe in oil and gas transmission medium. However, corrosion resistance of carbon steel armors has yet to beimproved. In this study, the relationship between corrosion resistance and pearlite fraction in the plain carbon steels hasbeen investigated through the application of pulsed electric current. Based on immersion test and electrochemical mea-surement, pulsed electric current increases the corrosion resistance of the plain carbon steels by reducing the fraction ofpearlite phase. Pitting corrosion, which tends to initiate by galvanic corrosion of ferrite and cementite, is therefore inhibiteddue to the decrease in pearlite fraction (mixture of ferrite and cementite) under electropulsing.
基金This work was financially supported by the National Key R&D Program of China(No.2020YFA0714900)the National Natural Science Foundation of China(Nos.51874023,U1860206,51871221.51671189 and 51971231)+1 种基金the Fundamental Research Funds for the Central Universities(No.FRF-TP-20-02B)the Recruitment Program of Global Experts and the Ministry of Science and Technology of China(Nos.2017YFA0700703 and 2019YFA0705304).
文摘In this study,high density electric current pulse(ECP)treatment was introduced instead of the conventional solution treatment,and theγ′phase was completely dissolved under the ECP treatment within only several milliseconds at 1148°C.Due to the extremely short treatment time and high cooling rate,the growth ofγ-phase matrix grain andγ′phase precipitate was effectively retarded.By comparing with the conventional heat process,the grain size of ECP treated sample was controlled to about 15μm,the size of the re-precipitatedγ′phase reduced from 65 to 35 nm,and the number density ofγ′precipitate increased from 1.46×108 to 3.03×108/mm2.The Vickers hardness,ultimate tensile strength and yield strength of the ECP treated sample were significantly improved.According to the theoretical derivation of kinetics,the ECP treatment introduces an extra electrical free energy which promoted the dissolution ofγ′phase.The ECP treatment may provide a new method for solution treatment of the Ni-based superalloy.
基金supported by the Science and Technology Innovation Major Project of Ningbo(No.2019B10101)the National Natural Science Foundation of China(Nos.U21B2082,U1860206,51601011,51874023)+1 种基金the Fundamental Research Funds for the Central Universities(No.FRF-TP-20-04B)the Recruitment Program of Global Experts,and the State Grid Scientifi c and Technological Research Program of China(No.5211DS17001X)。
文摘Controlling the precipitation through thermomechanical treatment is an important method to improve the corrosion resistance of Al–Cu–Mg alloys. In this study, the corrosion behaviors of Al–Cu–Mg alloys in the solution-treated state and retrogressiontreated state under cold rolling deformation and then natural aging were investigated. In the solution-treated series alloys, the cold-rolled deformation improved the resistance to intergranular corrosion by suppressing the precipitation of the S-phase on the grain boundaries. The increased pitting potential and corrosion potential were related to the increased concentration of solute atoms within the grain interiors and the eliminated S-phase on grain boundaries. In the retrogression-treated series alloys, the 30% cold rolling deformation stimulated the growth of the S-phase and transformed the S-phase distribution from discontinuous to continuous on the grain boundaries, thereby changing the pitting corrosion to the network corrosion morphology. The precipitation of the S-phase with large dimension within the grain interiors contributed to the decreased pitting potential and corrosion potential.