Metastable β-Ti alloys exhibiting twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) generally have excellent ductility, but typically at the expense of relatively low yield strengths whi...Metastable β-Ti alloys exhibiting twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) generally have excellent ductility, but typically at the expense of relatively low yield strengths which has restricted their widespread use. Our work shows that interstitial oxygen can be employed to regulate β phase stability to significantly enhance both strength and ductility of TWIP/TRIP alloys. For a Ti-32Nb wt.% base alloy, inclusion of 0.3 wt.% O enhanced ductility by more than 140 %, reaching up to 54 % strain, and improved the tensile yield strength by over 95 % to 632 MPa. Compared to other common engineering alloys such as Ti-45Nb, elongation was increased by 29 %, and the yield strength increased by 182 MPa, respectively. Here, we elucidate on impacts of oxygen doping on TWIP/TRIP behaviors in the Ti-32Nb alloy. We reveal that oxygen regulates the critical stress for martensitic transformation, twinning, and dislocation slip. At lower oxygen doping concentrations (≤0.3 wt.% O), multi-stage martensitic transformation and martensitic twinning resulted in high ductility. In higher oxygen content alloys (≥0.5 wt.% O), deformation occurred initially via twinning, while strain induced martensite was subsequently induced in retained β phase regions. Oxygen concentrations control the deformation mechanisms, providing a flexible means to synergistically balance an alloy's strength and ductility. The use of oxygen to enhance stability of the β phase and regulate deformation behaviors is a promising new approach for creating high-performance TWIP/TRIP metastable β-Ti alloys with outstanding mechanical properties.展开更多
Carbon-based materials have been widely applied for pollutant removal relying on their rich pore structure,functional groups,chemical stability,and expandability.However,the traditional manufacturing process of carbon...Carbon-based materials have been widely applied for pollutant removal relying on their rich pore structure,functional groups,chemical stability,and expandability.However,the traditional manufacturing process of carbon materials based on organic compounds pyrolysis is high energy-consuming and high-emission,which is not conducive to addressing the climate crisis and achieving the goal of carbon neutrality.Molten salt electrolysis technology enables the direct capture and reduction of CO_(2)to produce solid carbon,resulting in significant environmental benefits while achieving carbon emissions reduction.The molten salt also has a purification function,enabling the production of high-purity carbon materials.The kinetics of the electrochemical reduction process can be easily controlled,and the co-reduction of multiple elements provides convenience for the in-situ optimization of carbon material structure and the expansion of its applications.Therefore,this review focuses on the thermodynamics&kinetics processes of molten salt capture and electrochemical reduction of CO_(2)to prepare carbon materials.It further reviews the recent research progress on the preparation of carbon materials for pollutant removal based on molten salt electrochemical processes for the first time.Finally,we analyze the advantages and challenges of the current molten salt electrochemical processes and offers prospects for future research directions.展开更多
Geopolymer is a material with high early strength.However,the insufficient durability properties,such as long-term strength,acid-base resistance,freeze-thaw resistance,leaching toxicity,thermal stability,sulfate resis...Geopolymer is a material with high early strength.However,the insufficient durability properties,such as long-term strength,acid-base resistance,freeze-thaw resistance,leaching toxicity,thermal stability,sulfate resistance and carbonation resistance,restrain its practical application.Herein,a longterm stable geopolymer composite with high final strength(ASK1)was synthesized from shell coal gasification fly ash(SFA)and steel slag(SS).Additionally,a geopolymer composite with high early strength(ASK2)was also synthesized for comparison.The results showed that ASK1 exhibited better performance on freezing-thawing resistance,carbonization resistance and heavy metals stabilization compared to the ASK2 at long-term curing.Raising the curing temperature could accelerate the unconfined compressive strength(UCS)development at initial curing ages of 3 to 7 d.Both ASK1 and ASK2 exhibited excellent acid-base and sulfate corrosion resistance.An increase for UCS was seen under KOH solution and MgSO_(4)solution corrosion for ASK1.All leaching concentrations of heavy metals out of the two geopolymers were below the standard threshold,even after 50 freezingthawing cycles.Both ASK1 and ASK2 geopolymer concrete exhibited higher sustainability and economic efficiency than Portland cement concrete.The result of this study not only provides a suitable way for the utilization of industrial solid waste in civil and environmental engineering,but also opens a new approach to improve the long-term stabilities of the geopolymers.展开更多
基金supported by the Key R&D Program of Zhejiang(No.KZ7240079).
文摘Metastable β-Ti alloys exhibiting twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) generally have excellent ductility, but typically at the expense of relatively low yield strengths which has restricted their widespread use. Our work shows that interstitial oxygen can be employed to regulate β phase stability to significantly enhance both strength and ductility of TWIP/TRIP alloys. For a Ti-32Nb wt.% base alloy, inclusion of 0.3 wt.% O enhanced ductility by more than 140 %, reaching up to 54 % strain, and improved the tensile yield strength by over 95 % to 632 MPa. Compared to other common engineering alloys such as Ti-45Nb, elongation was increased by 29 %, and the yield strength increased by 182 MPa, respectively. Here, we elucidate on impacts of oxygen doping on TWIP/TRIP behaviors in the Ti-32Nb alloy. We reveal that oxygen regulates the critical stress for martensitic transformation, twinning, and dislocation slip. At lower oxygen doping concentrations (≤0.3 wt.% O), multi-stage martensitic transformation and martensitic twinning resulted in high ductility. In higher oxygen content alloys (≥0.5 wt.% O), deformation occurred initially via twinning, while strain induced martensite was subsequently induced in retained β phase regions. Oxygen concentrations control the deformation mechanisms, providing a flexible means to synergistically balance an alloy's strength and ductility. The use of oxygen to enhance stability of the β phase and regulate deformation behaviors is a promising new approach for creating high-performance TWIP/TRIP metastable β-Ti alloys with outstanding mechanical properties.
基金supported by the National Natural Science Foundation of China(Nos.52200143,51979011 and 52276208)the Natural Science Foundation of Hubei Province(No.2024AFB546)the Fundamental Research Funds for Central Public Welfare Research Institutes(Nos.CKSF2023302/CL and CKSF2023314/CL).
文摘Carbon-based materials have been widely applied for pollutant removal relying on their rich pore structure,functional groups,chemical stability,and expandability.However,the traditional manufacturing process of carbon materials based on organic compounds pyrolysis is high energy-consuming and high-emission,which is not conducive to addressing the climate crisis and achieving the goal of carbon neutrality.Molten salt electrolysis technology enables the direct capture and reduction of CO_(2)to produce solid carbon,resulting in significant environmental benefits while achieving carbon emissions reduction.The molten salt also has a purification function,enabling the production of high-purity carbon materials.The kinetics of the electrochemical reduction process can be easily controlled,and the co-reduction of multiple elements provides convenience for the in-situ optimization of carbon material structure and the expansion of its applications.Therefore,this review focuses on the thermodynamics&kinetics processes of molten salt capture and electrochemical reduction of CO_(2)to prepare carbon materials.It further reviews the recent research progress on the preparation of carbon materials for pollutant removal based on molten salt electrochemical processes for the first time.Finally,we analyze the advantages and challenges of the current molten salt electrochemical processes and offers prospects for future research directions.
基金funded by the Jiangxi Academy of Water Science and Engineering Open Project Fund(No.2021SKSG04)the National Natural Science Foundation of China(No.51979011)+1 种基金the Central Non-Profit Scientific Research Fund for Institutes(Nos.CKSF2021483/CL,CKSF2023359/HL,and CKSF2023397/HL)the Knowledge Innovation Program of Science and Technology Bureau of Wuhan,China(No.CKSD2022360/CL)。
文摘Geopolymer is a material with high early strength.However,the insufficient durability properties,such as long-term strength,acid-base resistance,freeze-thaw resistance,leaching toxicity,thermal stability,sulfate resistance and carbonation resistance,restrain its practical application.Herein,a longterm stable geopolymer composite with high final strength(ASK1)was synthesized from shell coal gasification fly ash(SFA)and steel slag(SS).Additionally,a geopolymer composite with high early strength(ASK2)was also synthesized for comparison.The results showed that ASK1 exhibited better performance on freezing-thawing resistance,carbonization resistance and heavy metals stabilization compared to the ASK2 at long-term curing.Raising the curing temperature could accelerate the unconfined compressive strength(UCS)development at initial curing ages of 3 to 7 d.Both ASK1 and ASK2 exhibited excellent acid-base and sulfate corrosion resistance.An increase for UCS was seen under KOH solution and MgSO_(4)solution corrosion for ASK1.All leaching concentrations of heavy metals out of the two geopolymers were below the standard threshold,even after 50 freezingthawing cycles.Both ASK1 and ASK2 geopolymer concrete exhibited higher sustainability and economic efficiency than Portland cement concrete.The result of this study not only provides a suitable way for the utilization of industrial solid waste in civil and environmental engineering,but also opens a new approach to improve the long-term stabilities of the geopolymers.
