To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the...To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.展开更多
Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding str...Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.展开更多
This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C s...This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.展开更多
An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior du...An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior during Mg-Ti friction welding process. The results show that the friction coefficient mainly experiences two steady stages. The first steady stage corresponds to the Coulomb friction with material abrasion. The second steady stage corresponds to the stick friction with fully plastic flow. Moreover, the increasing rates of axial displacement, temperature and friction coefficient are obviously enhanced with the increase of rotation speed and axial pressure. It can also be found that the there exists rapid diffusion phenomenon in the Mg-Ti friction welding system. The large deformation activated diffusion coefficient is about 105 higher than that activated by thermal.展开更多
Understanding the influencing factors of ecosystem services(ESs)and their relationships is essential for sustainable ecosystem management in degraded alpine ecosystems.There is a lack of integrated multi-model approac...Understanding the influencing factors of ecosystem services(ESs)and their relationships is essential for sustainable ecosystem management in degraded alpine ecosystems.There is a lack of integrated multi-model approaches to explore the multidimensional influences on ESs and their relationships in alpine ecosystems.Taking the Daxing'anling forest area,Inner Mongolia(DFAIM)as a case study,this study used the integrated valuation of ecosystem services and trade-offs(InVEST)model to quantify four ESs—soil conservation(SC),water yield(WY),carbon storage(CS),and habitat quality(HQ)—from 2013 to 2018.We adopted root mean square deviation(RMSD)and coupling coordination degree models(CCDM)to analyze their relationships,and integrated three complementary approaches—optimal parameter-based geographical detector model(OPGDM),gradient boosting regression tree model(GBRTM),and quantile regression model(QRM)—to reveal multidimensional influencing factors.Key findings include the following:(1)From 2013 to 2018,WY,SC,and HQ declined while CS increased.WY was primarily influenced by mean annual precipitation(MAP),forest ratio(RF),and soil bulk density(SBD);CS and HQ by RF and population density(PD);and SC by slope(S),RF,and MAP.Mean annual temperature(MAT),gross domestic product(GDP),and road network density(RND)showed increasing negative impacts.(2)Low trade-off intensity(TI<0.15)dominated all ES pairs,with RF,MAP,PD,and normalized difference vegetation index(NDVI)being the dominant factors.The factor interactions primarily showed two-factor enhancement patterns.(3)The average coupling coordination degree(CCD)of the four ESs was low and declined over time,with low-CCD areas becoming increasingly prevalent.RF,S,SBD,and NDVI positively influenced CCD,while PD,MAT,GDP,and RND had increasing negative impacts,with over 62%of the factor interactions exceeding the individual factor effects.In summary,ES supply generally decreased.Local relationships showed moderate coordination,while overall relationships indicated primary dysfunction.Land use and natural factors primarily shaped these ES and their relationships,while climate and socioeconomic changes diminished ES supply and intensified competition.We recommend enhancing the resilience of natural systems rather than replacing them,establishing climate adaptation monitoring systems,and promoting conservation tillage and cross-departmental coordination mechanisms for collaborative ES optimization.These results provide valuable insights into the sustainable management of alpine ecosystems.展开更多
Alkali treatments with three concentrations were used to modify a microarc-oxidized(MAO) coating on titanium alloy surface in order to further improve its surface bioactivity. Morphology, chemical compositions and pha...Alkali treatments with three concentrations were used to modify a microarc-oxidized(MAO) coating on titanium alloy surface in order to further improve its surface bioactivity. Morphology, chemical compositions and phase constitues, roughness, contact angle and apatite induction of the alkali-treated coatings were studied and compared. Scanning electron microscope(SEM) was applied to observe the morphologies, X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to detect the phase constitutes and chemical compositions, a surface topography profilometer was used to analyze the surface roughness, and contact angle was measured by liquid drop method. Alkali treatements result in the formation of Na2Ti6O13 and Na2Ti3O7 phase on the MAO coating, which leads to the increase of surface roughness and the decrease of contact angle. Experimental results showed that the apatite induction of the alkali-treated coatings was dependent on the applied alkali concentrations during treatments, and Na+concentration can promote the formation of apatite phase.展开更多
In order to overcome the embrittlement of metastable titanium alloys caused by the precipitation ofωiso phase during aging,regulation of isothermalωprecipitation was investigated in Ti−15Mo alloy.The results show th...In order to overcome the embrittlement of metastable titanium alloys caused by the precipitation ofωiso phase during aging,regulation of isothermalωprecipitation was investigated in Ti−15Mo alloy.The results show that the sample is brittle when direct aging(A)is applied at 350℃for 1 h after solution treatment(ST).If pre-deformation(D)is performed on the ST sample to induce{332}twins and secondaryα″phase,subsequent aging at 350℃(STDA350)improves the strength to 931 MPa with a good ductility of about 20%maintained.However,when aging is performed at 400℃or 450℃(STDA400/450),the strength can be further improved,but the ductility is dramatically reduced.Atomic-scale characterizations show that the partial collapse ofωphase in the STDA350 sample effectively eliminates aging-induced embrittlement,but complete collapse leads to poor ductility in the STDA400/450 sample.展开更多
Catalytic oxidation desulfurization(CODS)technology has shown great promise for diesel desulfurization by virtue of its low cost,mild reaction conditions,and superior desulfurization performance.Herein,a series of FeM...Catalytic oxidation desulfurization(CODS)technology has shown great promise for diesel desulfurization by virtue of its low cost,mild reaction conditions,and superior desulfurization performance.Herein,a series of FeMoO_(x)/LaTiO_(y)-z samples with diverse Fe/Mo ratios were prepared via a facile citric acid-assisted method.The impact of Fe incorporation on the dispersion and surface elemental states of Mo species,as well as oxygen species content of the synthesized FeMoO_(x)/LaTiO_(y)-z catalysts were systematically characterized using TEM,BET,UV-vis DRS,XPS,XANES,and reaction kinetics,and their CODS performances were examined for 4,6-DMDBT removal.Experimental results demonstrated that Fe/Mo ratio significantly affected the Ti−O bond strength,surface dispersion and electronic structure of Mo O_(2)species on FeMoO_(x)/LaTiO_(y)-z catalysts.FeMoO_(x)/LaTiO_(y)-2 catalyst showed outstanding cycling durability and the best CODS performance with almost 100%removal of 4,6-DMDBT from model oil within 75 min due to its proper MoO3 dispersion,optimal redox property,and the most oxygen vacancy concentration.Nevertheless,further enhancing Fe content led to the increased dispersion of Mo species,while the decrease active Mo species as well as the increase of steric effect for 4,6-DMDBT accessing to the catalytic reactive sites considerably increase the apparent activation energy of FeMoO_(x)/LaTiO_(y)-z(z>2)catalysts during the CODS process,thereby seriously suppressing their CODS performances.Moreover,Radical trapping experiments reveal that the·,generated by the activation of O_(2)at the active sites,catalytic oxidized 4,6-DMDBT to the product of 4,6-DMDBTO_(2),thereby enabling both deep desulfurization and recovery of high-value 4,6-DMDBTO_(2).These findings offer an alternative strategy to achieve ultra deep desulfurization as well as separate and recover high economic value sulfone substances from diesel.展开更多
基金National Natural Science Foundation of China(51504138,51674118,52271177)Hunan Provincial Natural Science Foundation of China(2023JJ50181)Supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2024-022)。
文摘To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.
基金supported by the National Key R&D Program of China (No. 2018YFA0707300)the National Natural Science Foundation of China (No. 52374376)the Introduction Plan for High end Foreign Experts, China (No. G2023105001L)。
文摘Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.
文摘This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.
基金Projects (51101126, 51071123) supported by the National Natural Science Foundation of ChinaProjects (20110491684, 2012T50817) supported by the China Postdoctoral Science FoundationProject (20110942K) supported by the Open Fund of State Key Laboratory of Powder Metallurgy of Central South University, China
文摘An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior during Mg-Ti friction welding process. The results show that the friction coefficient mainly experiences two steady stages. The first steady stage corresponds to the Coulomb friction with material abrasion. The second steady stage corresponds to the stick friction with fully plastic flow. Moreover, the increasing rates of axial displacement, temperature and friction coefficient are obviously enhanced with the increase of rotation speed and axial pressure. It can also be found that the there exists rapid diffusion phenomenon in the Mg-Ti friction welding system. The large deformation activated diffusion coefficient is about 105 higher than that activated by thermal.
基金funded primarily by the Central Public Welfare Research Institutes Basic Research Business Funds to Support the Administration’s Central Work Project(Grant No.CAFYBB2023ZA003-4)the National Natural Science Foundation of China(Grant Nos.31170593 and 31570633)National Forestry and Grassland Administration Forestry Under the Project“Forestry Major Issues Research”(Grant Nos.500102-1776 and 500102-5110).
文摘Understanding the influencing factors of ecosystem services(ESs)and their relationships is essential for sustainable ecosystem management in degraded alpine ecosystems.There is a lack of integrated multi-model approaches to explore the multidimensional influences on ESs and their relationships in alpine ecosystems.Taking the Daxing'anling forest area,Inner Mongolia(DFAIM)as a case study,this study used the integrated valuation of ecosystem services and trade-offs(InVEST)model to quantify four ESs—soil conservation(SC),water yield(WY),carbon storage(CS),and habitat quality(HQ)—from 2013 to 2018.We adopted root mean square deviation(RMSD)and coupling coordination degree models(CCDM)to analyze their relationships,and integrated three complementary approaches—optimal parameter-based geographical detector model(OPGDM),gradient boosting regression tree model(GBRTM),and quantile regression model(QRM)—to reveal multidimensional influencing factors.Key findings include the following:(1)From 2013 to 2018,WY,SC,and HQ declined while CS increased.WY was primarily influenced by mean annual precipitation(MAP),forest ratio(RF),and soil bulk density(SBD);CS and HQ by RF and population density(PD);and SC by slope(S),RF,and MAP.Mean annual temperature(MAT),gross domestic product(GDP),and road network density(RND)showed increasing negative impacts.(2)Low trade-off intensity(TI<0.15)dominated all ES pairs,with RF,MAP,PD,and normalized difference vegetation index(NDVI)being the dominant factors.The factor interactions primarily showed two-factor enhancement patterns.(3)The average coupling coordination degree(CCD)of the four ESs was low and declined over time,with low-CCD areas becoming increasingly prevalent.RF,S,SBD,and NDVI positively influenced CCD,while PD,MAT,GDP,and RND had increasing negative impacts,with over 62%of the factor interactions exceeding the individual factor effects.In summary,ES supply generally decreased.Local relationships showed moderate coordination,while overall relationships indicated primary dysfunction.Land use and natural factors primarily shaped these ES and their relationships,while climate and socioeconomic changes diminished ES supply and intensified competition.We recommend enhancing the resilience of natural systems rather than replacing them,establishing climate adaptation monitoring systems,and promoting conservation tillage and cross-departmental coordination mechanisms for collaborative ES optimization.These results provide valuable insights into the sustainable management of alpine ecosystems.
基金Projects(51172050,51102060,51302050)supported by the National Natural Science Foundation of ChinaProject(HIT.ICRST.2010009)supported by the Fundamental Research Funds for Central Universities,ChinaProject(HIT.NSRIF.2014129)supported by the Natural Scientific Research Innovation Foundation in Harbin Institute of Technology,China
文摘Alkali treatments with three concentrations were used to modify a microarc-oxidized(MAO) coating on titanium alloy surface in order to further improve its surface bioactivity. Morphology, chemical compositions and phase constitues, roughness, contact angle and apatite induction of the alkali-treated coatings were studied and compared. Scanning electron microscope(SEM) was applied to observe the morphologies, X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to detect the phase constitutes and chemical compositions, a surface topography profilometer was used to analyze the surface roughness, and contact angle was measured by liquid drop method. Alkali treatements result in the formation of Na2Ti6O13 and Na2Ti3O7 phase on the MAO coating, which leads to the increase of surface roughness and the decrease of contact angle. Experimental results showed that the apatite induction of the alkali-treated coatings was dependent on the applied alkali concentrations during treatments, and Na+concentration can promote the formation of apatite phase.
基金the financial support from the National Natural Science Foundation of China (No. 52374380)the China Postdoctoral Science Foundation (Nos. 2023M730234, 2024T171126)。
文摘In order to overcome the embrittlement of metastable titanium alloys caused by the precipitation ofωiso phase during aging,regulation of isothermalωprecipitation was investigated in Ti−15Mo alloy.The results show that the sample is brittle when direct aging(A)is applied at 350℃for 1 h after solution treatment(ST).If pre-deformation(D)is performed on the ST sample to induce{332}twins and secondaryα″phase,subsequent aging at 350℃(STDA350)improves the strength to 931 MPa with a good ductility of about 20%maintained.However,when aging is performed at 400℃or 450℃(STDA400/450),the strength can be further improved,but the ductility is dramatically reduced.Atomic-scale characterizations show that the partial collapse ofωphase in the STDA350 sample effectively eliminates aging-induced embrittlement,but complete collapse leads to poor ductility in the STDA400/450 sample.
基金supported by the Natural Science Foundation of Guangdong Province(2024A1515010908,2025A1515011103)Opening Project of Hubei Key Laboratory of Plasma Chemistry and Advanced Materials(2024P11)+2 种基金Postdoctoral Fellowship Program of CPSF(GZC20233104)National Natural Science Foundation of China(22202087)Opening Project of Hubei Key Laboratory of Biomass Fibers and Eco-Dyeing&Finishing(STRZ202418)。
文摘Catalytic oxidation desulfurization(CODS)technology has shown great promise for diesel desulfurization by virtue of its low cost,mild reaction conditions,and superior desulfurization performance.Herein,a series of FeMoO_(x)/LaTiO_(y)-z samples with diverse Fe/Mo ratios were prepared via a facile citric acid-assisted method.The impact of Fe incorporation on the dispersion and surface elemental states of Mo species,as well as oxygen species content of the synthesized FeMoO_(x)/LaTiO_(y)-z catalysts were systematically characterized using TEM,BET,UV-vis DRS,XPS,XANES,and reaction kinetics,and their CODS performances were examined for 4,6-DMDBT removal.Experimental results demonstrated that Fe/Mo ratio significantly affected the Ti−O bond strength,surface dispersion and electronic structure of Mo O_(2)species on FeMoO_(x)/LaTiO_(y)-z catalysts.FeMoO_(x)/LaTiO_(y)-2 catalyst showed outstanding cycling durability and the best CODS performance with almost 100%removal of 4,6-DMDBT from model oil within 75 min due to its proper MoO3 dispersion,optimal redox property,and the most oxygen vacancy concentration.Nevertheless,further enhancing Fe content led to the increased dispersion of Mo species,while the decrease active Mo species as well as the increase of steric effect for 4,6-DMDBT accessing to the catalytic reactive sites considerably increase the apparent activation energy of FeMoO_(x)/LaTiO_(y)-z(z>2)catalysts during the CODS process,thereby seriously suppressing their CODS performances.Moreover,Radical trapping experiments reveal that the·,generated by the activation of O_(2)at the active sites,catalytic oxidized 4,6-DMDBT to the product of 4,6-DMDBTO_(2),thereby enabling both deep desulfurization and recovery of high-value 4,6-DMDBTO_(2).These findings offer an alternative strategy to achieve ultra deep desulfurization as well as separate and recover high economic value sulfone substances from diesel.
