To clarify the densification behavior,deformation response and strengthening mechanisms of selective laser melted(SLM)Mg-RE alloys,this study systematically investigates a representative WE43 alloy via advanced materi...To clarify the densification behavior,deformation response and strengthening mechanisms of selective laser melted(SLM)Mg-RE alloys,this study systematically investigates a representative WE43 alloy via advanced material characterization techniques.A suitable laser output mode fell into the transition mode,allowing for the fabrication of nearly full-density samples(porosity=0.85±0.021%)with favorable mechanical properties(yield strength=351 MPa,ultimate tensile strength=417 MPa,the elongation at break=6.5%and microhardness=137.9±6.15 HV_(0.1))using optimal processing parameters(P=80 W,v=250 mm/s and d=50μm).Viscoplastic self-consistent analysis and transmission electron microscopy observations reveal that the plastic deformation response of the SLM Mg-RE alloys is primarily driven by basal and prismatic slips.Starting from a random texture before deformation(maximum multiple of ultimate density,Max.MUD=3.95),plastic stretching led the grains to align with the Z-axis,finally resulting in a{0001}<1010>texture orientation after fracture(Max.MUD=8.755).Main phases of the SLM state are mainly composed ofα-Mg,Mg_(24)Y_(5) andβ'-Mg_(41)Nd_(5),with an average grain size of only 4.27μm(about a quarter of that in the extruded state),resulting in a favorable strength-toughness ratio.Except for the nano-β'phase and semi-coherent Mg_(24)Y_(5) phase(mismatch=16.12%)around the grain boundaries,a small amount of nano-ZrO_(2) and Y_(2)O_(3) particles also play a role in dispersion strengthening.The high mechanical properties of the SLM state are chiefly attributed to precipitation hardening(44.41%),solid solution strengthening(34.06%)and grain boundary strengthening(21.53%),with precipitation hardening being predominantly driven by dislocation strengthening(67.77%).High-performance SLM Mg-RE alloy components were manufactured and showcased at TCT Asia 2024,receiving favorable attention.This work underscores the significant application potential of SLM Mg-RE alloys and establishes a strong foundation for advancing their use in the biomedical fields.展开更多
The AlMgScZr high-strength aluminum alloy fabricated by selective laser melting(SLM)technology exhibits a“bimodal microstructure”,resulting in significant non-uniform deformation during thermal deformation.This stud...The AlMgScZr high-strength aluminum alloy fabricated by selective laser melting(SLM)technology exhibits a“bimodal microstructure”,resulting in significant non-uniform deformation during thermal deformation.This study investigates the flow behavior of SLM-processed AlMgScZr aluminum alloy utilizing the Gleeble-1500D thermal simulation machine.The true stress-strain curves were amended based on the friction theory.Through determining the Zener-Hollomon parameters,the correlation between flow stress,deformation temperature,and strain rate during the high-temperature thermoplastic deformation of SLM-processed AlMgScZr aluminum alloy with a“bimodal microstructure”was established.In addition,the microstructural evolution during thermal deformation was analyzed.The results indicated that the predicted flow stress values obtained from the Arrhenius constitutive equation with coupled correction of thermal deformation parameters closely matched the experimental values.The correlation coefficient and the average absolute relative error of the corrected model were 0.999 and 2.766%,respectively,accurately predicting the thermoplastic deformation behavior of SLM-processed high-strength aluminum alloy with a“bimodal microstructure”.Furthermore,hot processing maps at different strains were established,identifying stable and unstable regions under different deformation conditions.Microstructural observations revealed different thermal deformation mechanisms under various deformation temperatures.Specifically,dynamic recrystallization characteristics dominated the microstructure at lower temperatures(300-360℃),while dynamic recovery was dominant at higher temperatures(390-500℃).展开更多
The effects of various heat treatments on the microstructures and mechanical properties of as-built selective laser melted Inconel 718 alloy were investigated through conventional and quasi-in-situ tensile tests.The c...The effects of various heat treatments on the microstructures and mechanical properties of as-built selective laser melted Inconel 718 alloy were investigated through conventional and quasi-in-situ tensile tests.The corresponding heat treatment processes include direct aging(DA),solution+aging(SA),and homogenization+aging(HA).The DA and SA samples preserve the melt pool configuration and grain size stability,while the precipitated phase characteristics reveal the refinement of the long-strip Laves phase and the appearance of theδphase,respectively.The HA process induces recrystallization and grain coarsening.The specimens exhibit enhanced strength concomitant with diminished elongation,which is likely attributed to the reduction of the geometrically necessary dislocation density and the intensified precipitation of theγ′′phase after heat treatment.Tensile plastic deformation displays notable strain concentration along grain boundaries.The dimensional alterations in precipitated phases were measured to quantitatively determine the impact of grain boundary,dislocation and precipitation strengthening on the yield strength after heat treatment.Precipitation strengthening encompasses coherent,order,and Orowan strengthening.A remarkable agreement is revealed between theoretical predictions and experimental results.Insights are offered for optimizing heat treatment processes to comprehend microstructural evolution effect on the mechanical properties of additive-manufactured metals.展开更多
A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructur...A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructure and the mechanism of grain refinement in TA15 titanium alloy during SSP treatment.Transmission electron microscopyand Rietveld refinement methods were employed.The residual stress and microhardness variations with depth were also characterized.The results show:(1)At the initial stage of deformation,plastic deformation is primarily accommodated through twinning and dislocation slip.(2)As the strain increases,twinning disappears,and dislocations interact to form tangles.Some dislocations annihilate and rearrange into subgrain boundaries,subdividing the original grains into subgrains.(3)With continued dislocation activity,the subgrain size decreases until nanocrystals are formed through the dynamic rotational recrystallization.SSP introduced compressive residual stress(CRS)in the near-surface layer of the material,with the maximum CRS of approximately−1141 MPa observed in the subsurface layer.It also induced work hardening,increasing the surface hardness to approximately 479 HV.However,the surface roughness increases,leading to a slight deterioration in surface quality.展开更多
In the original publication,mistakenly first and corresponding affiliation is given as:Thermoelectricity Technology Center,Hangzhou Dahe Thermo-Magnetics Co.Ltd,Hangzhou 310053,ChinaThe correct first and corresponding...In the original publication,mistakenly first and corresponding affiliation is given as:Thermoelectricity Technology Center,Hangzhou Dahe Thermo-Magnetics Co.Ltd,Hangzhou 310053,ChinaThe correct first and corresponding affiliation is:State Key Laboratory of Silicon Materials,School of Materials Science and Engineering,Zhejiang University,Hangzhou 310027,China.展开更多
Selective laser melting(SLM)has become a critical technique for manufacturing molds with conformal cooling channels to achieve high cooling efficiencies.A novel selective laser-melted 718HH plastic mold steel with an ...Selective laser melting(SLM)has become a critical technique for manufacturing molds with conformal cooling channels to achieve high cooling efficiencies.A novel selective laser-melted 718HH plastic mold steel with an excellent combination of strength and toughness was investigated.After SLM fabrication,quenching and tempering are conducted as post-printing heat treatment(PPHT)to improve the mechanical properties of the as-built samples.Both the microstructure and the corresponding mechanical properties were systematically studied.The results show that PPHT facilitates the complete martensite transformation.Meanwhile,the retained austenite(γ)phase was still found in the as-built samples.And high-density dislocations were dispersively distributed within the martensite matrix for both as-built and as-PPHTed samples.After PPHT,due to the recovery and recrystallization of martensite,reduced dislocation density and increased high-angle grain boundaries,the microhardness of the as-built samples decreased from 498.8±16.7 to 382.1±5.0 HV0.3.Correspondingly,the strength,including the ultimate tensile strength and yield strength,of the as-built and as-PPHTed samples also decreased from 1411.3±17.8 to 1208.7±3.2 MPa and 1267.3±11.7 to 1084.7±5.1 MPa,respectively.On the contrary,the value of impact energy significantly increased from 15.3±1.2 J(as-built)to 39.7±1.2 J(as-PPHTed).Notably,the mechanical properties of SLMed 718HH samples are significantly better than those of corresponding wrought samples.展开更多
Only a few studies have reported the efects of electrochemical hydrogenation on the tensile mechanical properties of additively manufactured Ti–6Al–4V alloy,in all of them the alloy was processed by laser powder-bed...Only a few studies have reported the efects of electrochemical hydrogenation on the tensile mechanical properties of additively manufactured Ti–6Al–4V alloy,in all of them the alloy was processed by laser powder-bed fusion.Furthermore,the efects of either hot isostatic pressing(HIP)or heat treatment(HT)post-treatments on the mechanical properties were not reported.Here,the Young’s modulus,ultimate tensile stress,and uniform(homogeneous)strain of as-built electron beam melted(EBM)Ti–6Al–4V alloys were studied using small tensile specimens before and after electrochemical hydrogenation,as well as before and after secondary processes of HIP at 920℃ and HT at 1000℃.The tensile properties of all hydrogenated alloys were signifcantly degraded compared to their non-hydrogenated counterparts.The yield stress could not be determined for all hydrogenated alloys,as failure occurred at a strain below 0.2%ofset.The uniform strain of the hydrogenated alloys was less than 1%,compared to 1%–5%for the non-hydrogenated alloys.The fracture mode of the hydrogenated alloys after HIP and HT revealed cleavage fracture,indicating increased brittleness.In the as-built hydrogenated alloy,the fracture mode varied with location:brittle fracture occurred near the surface due to the formation of a hydride layer,while a more ductile fracture with dimples was observed below this layer.展开更多
To improve the processability and mechanical properties of the selective laser melting(SLM)low Sc content Al−Mg−Sc−Zr alloy,Mn was used to partially replace Mg.The processability,microstructure,and mechanical properti...To improve the processability and mechanical properties of the selective laser melting(SLM)low Sc content Al−Mg−Sc−Zr alloy,Mn was used to partially replace Mg.The processability,microstructure,and mechanical properties of the SLM-fabricated Al−Mg−Mn−Sc−Zr alloy were systematically investigated by density measurement,microstructure characterization,and tensile testing.The results revealed that dense samples could be obtained by adjusting the SLM process parameters.The alloy exhibited a fine equiaxed-columnar bimodal grain microstructure.The presence of primary Al3Sc andα-Al(Mn,Fe)Si particles contributed to the grain refinement of the alloy with an average grain size of 4.63μm.Upon aging treatment at 350°C for 2 h,the strength and elongation of the alloy were simultaneously improved due to the precipitation of Al3Sc nanoparticles and the formation of the 9R phase.This study demonstrates that the strength−plasticity trade-off of the aluminum alloy can be overcome by utilizing SLM technology and subsequent post-heat treatment to induce the formation of the long-period stacked ordered phase.展开更多
Mercury（Hg） in the Arctic is a significant concern due to its bioaccumulative and neurotoxic properties, and the sensitivity of Arctic environments. Previous research has found high levels of Hg in snowpacks with hi...Mercury（Hg） in the Arctic is a significant concern due to its bioaccumulative and neurotoxic properties, and the sensitivity of Arctic environments. Previous research has found high levels of Hg in snowpacks with high chloride（Cl-） concentrations. We hypothesised that Cl- would increase Hg retention by decreasing Hg photoreduction to Hg（0） in melted Arctic snow. To test this, changes in Hg photoreduction kinetics in melted Alert, NU snow were quantified with changing Cl- concentration and UV intensity. Snow was collected and melted in Teflon bottles in May 2014, spiked with 0–10 μg/g Cl-, and irradiated with 3.52–5.78 W·m-2 UV（280–400 nm）radiation in a Luz Chem photoreactor. Photoreduction rate constants（k）（0.14–0.59 hr-1） had positive linear relationships with [Cl-], while photoreduced Hg amounts（Hg（Ⅱ）red） had negative linear relationships with [Cl-]（1287–64 pg in 200 g melted snow）. Varying UV and[Cl-] both altered Hg（Ⅱ）red amounts, with more efficient Hg stabilisation by Cl- at higher UV intensity, while k can be predicted by Cl- concentration and/or UV intensity, depending on experimental parameters. Overall, with future projections for greater snowpack Cl- loading,our experimental results suggest that more Hg could be delivered to Arctic aquatic ecosystems by melted snow（smaller Hg（Ⅱ）red expected）, but the Hg in the melted snow that is photoreduced may do so more quickly（larger k expected）.展开更多
To develop large-scale RP systems used to producing functional parts and large-sized models has become an urgentcall now. In this paper, a large-scale RP system, MEM600-l, based on the melted extrusion manufacturing (...To develop large-scale RP systems used to producing functional parts and large-sized models has become an urgentcall now. In this paper, a large-scale RP system, MEM600-l, based on the melted extrusion manufacturing (MEM)process has been developed successfully. And the key issues to develop such a system are discussed. Based on theactual forming experiment, it is concluded that the MEM600-l works reliably and the forming efficiency is muchhigher than its parallel equipments.展开更多
The characteristics of some elements in inoculant were analyzed.The effect of the morphology of instantaneous inoculant on its melting velocity was studied.When the inoculants pass through the same sieve number,the vo...The characteristics of some elements in inoculant were analyzed.The effect of the morphology of instantaneous inoculant on its melting velocity was studied.When the inoculants pass through the same sieve number,the volume and the ratio of surface area to volume are different.It is evident from the theoretical analysis and experiment under some conditions that the melting velocity of inoculant depends on the morphology of inoculant.The morphology of inoculant during production should be controlled carefully.展开更多
Irregular grains, high interfacial stresses and anisotropic properties widely exist in 3D-printed metallic materials, and this paper investigated the effects of heat treatment on the microstructural, mechanical and co...Irregular grains, high interfacial stresses and anisotropic properties widely exist in 3D-printed metallic materials, and this paper investigated the effects of heat treatment on the microstructural, mechanical and corrosion properties of 316 L stainless steel fabricated by selective laser melting. Sub-grains and low-angle boundaries exist in the as-received selective laser melted(SLMed) 316 L stainless steel. After heat treatment at 1050℃, the sub-grains and low-angle boundaries changed slightly, and the stress state and strength decreased to some extent due to the decrease of dislocation density. After heat treatment at 1200℃, the grains became uniform, and the dislocation cells vanished, which led to a sharp decline in the hardness and strength. However, the ductility was improved after recrystallization heat treatment.The passive film thickness and corrosion potential of the SLMed 316 L stainless steel decreased after heat treatment, and the pitting potential also decreased due to the accelerated transition from metastable to steady-state pitting;this accelerated transition was caused by the presence of weak passive films at the enlarged pores after heat treatment, especially for an adequate solid solution treatment.展开更多
Laser welding is a promising process for joining small components produced by selective laser melting (SLM) to fabricate the large-scale and complex-shaped parts. In the work, the morphology, microstructure, microhard...Laser welding is a promising process for joining small components produced by selective laser melting (SLM) to fabricate the large-scale and complex-shaped parts. In the work, the morphology, microstructure, microhardness, tensile properties and corrosion resistance of the laser welded stress-relieved SLMed 304 stainless steel joints are investigated, as the different sections of stress-relieved SLMed 304 stainless steel are joined. Results show that the SLMed 304 stainless steel plates have a good laser weldability. The microstructure of laser-welded joints consists of the cellular dendrites in austenite matrix within columnar grains, exhibiting a coarser dendrite structure, lower microhardness (~220HV) and tensile properties (tensile strength of ~750 MPa, and area reduction of ~27.6%), but superior corrosion resistance to those of SLMed plates. The dendrite arm spacing of the joints varies from ~3.7μm in center zone, to ~5.0 (xm in fusion zone, to ~2.5 in epitaxial zone. The SLMed anisotropy shows a negligible effect on the microstructure and performance of the laser-welded joints. The laser welding along the building directions of the SLMed base plates can induce a slightly finer dendritic structure and higher tensile properties.展开更多
Finite element modeling(FEM),microscopy,X-ray computed tomography(CT)and mechanical property tests were used to study the microstructure,porosity and mechanical properties of an AlSi10Mg alloy produced by selective la...Finite element modeling(FEM),microscopy,X-ray computed tomography(CT)and mechanical property tests were used to study the microstructure,porosity and mechanical properties of an AlSi10Mg alloy produced by selective laser melting(SLM).The simulation of the melt pool and thermal history under different energy densities produced an optimized result with an energy density of 44.5 J·mm-3.The high cooling rate during the SLM process significantly refined the previous a-Al dendrites.The growth direction of the network-like Al-Si eutectic structure at different orientations confirmed the anisotropic nature of the microstructure.Furthermore,the microhardness,tensile testing and fracture analysis results proved that there were no obvious distinctions in the strength between the transverse and longitudinal directions,and that the ductility was anisotropic,possibly due to the shape and distribution of the pores.The pores measured by X-ray CT at different energy densities confirmed that the sphericity of the pores was inversely related to pores volumes.With optimized processing conditions,the porosity of the selective laser melted sample decreased leading to the improved fabricated fuel system component via SLM.展开更多
In this study,the microstructure and tensile properties of selective laser melted AlSilOMg at elevated temperature were investigated with focus on the interfacial region.In-situ SEM and in-situ EBSD analysis were prop...In this study,the microstructure and tensile properties of selective laser melted AlSilOMg at elevated temperature were investigated with focus on the interfacial region.In-situ SEM and in-situ EBSD analysis were proposed to characterize the microstructural evolution with temperature.The as-fabricated AlSilOMg sample presents high tensile strength with the ultimate tensile strength(UTS)of~450 MPa and yield strength(YS)of~300 MPa,which results from the mixed strengthening mechanism among grain boundary,solid solution,dislocation and Orowan looping mechanism.When holding at the temperature below 200℃for 30 min,the micro structure presents little change,and only a slight decrement of yield strength appears due to the relief of the residual stress.However,when the holding temperature further increases to 300℃and 400℃,the coarsening and precipitation of Si particles inα-Al matrix occur obviously,which leads to an obvious decrease of solid solution strength.At the same time,matrix softening and the weakness of dislocation strengthening also play important roles.When the holding temperature reaches to 400℃,the yield strength decreases significantly to about 25 MPa which is very similar to the as-cast Al alloy.This might be concluded that the YS is dominated by the matrix materials.Because the softening mechanism counteracts work hardening,the extremely high elongation occurs.展开更多
In the context of global carbon neutrality, the application of lightweight magnesium alloys is becoming increasingly attractive. In this study, selective laser melting(SLM) was employed to achieve nearly full dense an...In the context of global carbon neutrality, the application of lightweight magnesium alloys is becoming increasingly attractive. In this study, selective laser melting(SLM) was employed to achieve nearly full dense and crack-free AZ91D components with fine equiaxed grain structure. The formation mechanism of typical pore defects(gas pore, lack-of-fusion pore and keyhole pore) and melting modes(keyhole mode and conduction mode) were systematically studied by varying the laser power and scanning speed. The morphology and volume fraction of the pores under different processing conditions were characterized. A criterion based on the depth-to-width ratio of the melt pool was established to identify different melting modes. The strength and ductility(tensile strength up to 340 MPa and uniform elongation of 8.9%)of the as deposited AZ91D are far superior to those of the casting components and are comparable to those of its wrought counterparts.The superior balance of strength and ductility of SLMed AZ91D, as well as the negligible anisotropic properties are mainly ascribed to the extremely fine equiaxed grain structure(with average grain size of ~1.2 μm), as well as the discontinuous distribution of β-Al_(12)Mg_(17) phases. It thus provides an alternative way to fabricate high-strength magnesium alloys with complex geometry.展开更多
For zone-melted （ZM） bismuth telluride-based alloys, which are widely commercially available for solidstate cooling and low-temperature power generation around room temperature, introducing point defects is the chie...For zone-melted （ZM） bismuth telluride-based alloys, which are widely commercially available for solidstate cooling and low-temperature power generation around room temperature, introducing point defects is the chief approach to improve their thermoelectric performance. Herein, we report the multiple effects of Se doping on thermoelectric performance of p-type Bi0.5Sb1,5Te3-xSex ＋ 3 wt% Te ZM ingots, which increases carrier concentration, reduces lattice thermal conductivity and deteriorates the carrier mobility. As a result, the peak figure of merit （ZT） is shifted to a higher temperature and a high ZT 1.2 at 350 K is obtained, due to the reduced thermal conductivity and suppressed intrinsic conduction. Further, decreasing Sb content is followed to optimize the room temperature performance and a ZT - 1.1 at 300 K is obtained. These results are significant for designing and optimizing the thermoelectric performance of commercial Bi0.5Sb1.5Te3＋ 3 wt% Te ZM alloys.展开更多
This work characterizes microstructural evolutions of electron beam melted(EBM) Ti-6 Al-4 V alloy modified via laser shock peening(LSP).The depth stress distribution and tensile properties of EBM Ti-6 Al-4 V alloy wer...This work characterizes microstructural evolutions of electron beam melted(EBM) Ti-6 Al-4 V alloy modified via laser shock peening(LSP).The depth stress distribution and tensile properties of EBM Ti-6 Al-4 V alloy were measured before and after LSP.The results indicate that microstructure consists of β phase with 7.2%±0.4% vol.% and balance α lamellar in EBM sample,and the α lamella was refined into nano-equiaxed grains and submicro-equiaxed grains after LSP.The dominant refinement mechanism is revealed during LSP.Stacking faults were found in the LSP-treated sample,and their corresponding planes were determined as(0001) basal plane,(1010) prismatic plane,and(1011) pyramidal plane obtained by high resolution transmission electron microscopy.The subgrains and high-angle grains formed during dynamic recrystallization were identified by selected area electron diffraction pattern.The LSP treatment produces a significantly residual compressive stress approximately-380 MPa with the depth of compressive stress layer reaching 450 μm.Strength and elongation of the EBM sample were significantly increased after LSP.The strength and ductility enhancements are attributed to compre s sive stress,grain refinement and grain gradient distribution of α phase.展开更多
Although using elemental powder mixtures may provide broad alloy selection at low cost for selective laser melting(SLM), there is still a concern on the resultant microstructural and chemical homogeneity of the produc...Although using elemental powder mixtures may provide broad alloy selection at low cost for selective laser melting(SLM), there is still a concern on the resultant microstructural and chemical homogeneity of the produced parts. Hence, this work investigates the microstructure and mechanical properties of a SLM-produced Ti-35 Nb composite(in wt%) using elemental powder. The microstructural characteristics including ? phase, undissolved Nb particles and chemical homogeneity were detailed investigated.Nanoindentation revealed the presence of relatively soft undissolved Nb particles and weak interface bonding around Nb-rich regions in as-SLMed samples. Solid-solution treatment can not only improve chemical homogeneity but also enhance bonding through grain boundary strengthening, resulting in43 % increase in tensile elongation for the heat-treated Ti-35 Nb compared to the as-SLMed counterpart. The analyses of tensile fractures and shear bands further confirmed the correlation between the different phases and the ductility of Ti-35 Nb. In particular, the weak bonding between undissolved Nb and the matrix in the as-SLMed sample reduces its ductility while the ? grains in solid-solution treated Ti-Nb alloy can induce a relatively stable plastic flow therefore better ductility. This work sheds insight into the understanding of homogenization of microstructure and phases of SLM-produced alloys from an elemental powder mixture.展开更多
In this study,the CoCrW-x Cu alloys(x=2,3 and 4 wt%)were fabricated using selective laser melting(abbreviated as Co-2 Cu,Co-3 Cu and Co-4Cu)with the purpose of reducing the inflammation responses and the activity of o...In this study,the CoCrW-x Cu alloys(x=2,3 and 4 wt%)were fabricated using selective laser melting(abbreviated as Co-2 Cu,Co-3 Cu and Co-4Cu)with the purpose of reducing the inflammation responses and the activity of osteoclast.The metal ions releasing test showed that when the Cu content was less than 4 wt%,the releasing amount of Co and Cr ions was very small;however,when 4 wt%Cu was added in the CoCrW based alloy,the quantity of Co ions was significantly elevated with respect to the other groups due to the segregation of precipitates in the matrix;the Cu2+ion quantity of the Co-2Cu,Co-3Cu and Co-4Cu alloys were 0.05,0.09 and 0.27 g/(L cm2)after 7 d immersion,respectively;the RT-q PCR and ELISA data indicated that the expression levels of the pro-inflammatory cytokines(TNF-αand IL-6)were down-regulated in the Co-3Cu and Co-4Cu groups,whereas the expression level of the anti-inflammatory cytokine(IL-10)was up-regulated in all CoCrW-x Cu alloys;meanwhile,the Cu-containing CoCrW alloys significantly down-regulated the expression of the NF-B signal pathway in a Cu content-dependent manner,and the downstream transcription factors of NF-B signal pathway including NFATc1,TRAP and Cath-K were also down-regulated via potentially manipulating the NF-B signal pathway.After comprehensive consideration,it is considered that the Co-3Cu alloy is a potential material for self-alleviating inflammatory responses.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFC2406000)the Guangdong Basic and Applied Basic Research Foundation(2024A1515011024)+5 种基金the Guangzhou Science and Technology Project(2024A04J4943)the Guangdong Academy of Sciences Development Special Fund Project(2022GDASZH-2022010107)the Guangdong province Science and Technology Plan Projects(2023B1212120008,2023B1212060045)the GDAS Projects of International cooperation platform of Science and Technology(2022GDASZH-2022010203-003)Special Support Foundation of Guangdong Province(2023TQ07Z559)Shenzhen Basic Research Project(JCYJ20210324120001003 and JCYJ20220531091802006)。
文摘To clarify the densification behavior,deformation response and strengthening mechanisms of selective laser melted(SLM)Mg-RE alloys,this study systematically investigates a representative WE43 alloy via advanced material characterization techniques.A suitable laser output mode fell into the transition mode,allowing for the fabrication of nearly full-density samples(porosity=0.85±0.021%)with favorable mechanical properties(yield strength=351 MPa,ultimate tensile strength=417 MPa,the elongation at break=6.5%and microhardness=137.9±6.15 HV_(0.1))using optimal processing parameters(P=80 W,v=250 mm/s and d=50μm).Viscoplastic self-consistent analysis and transmission electron microscopy observations reveal that the plastic deformation response of the SLM Mg-RE alloys is primarily driven by basal and prismatic slips.Starting from a random texture before deformation(maximum multiple of ultimate density,Max.MUD=3.95),plastic stretching led the grains to align with the Z-axis,finally resulting in a{0001}<1010>texture orientation after fracture(Max.MUD=8.755).Main phases of the SLM state are mainly composed ofα-Mg,Mg_(24)Y_(5) andβ'-Mg_(41)Nd_(5),with an average grain size of only 4.27μm(about a quarter of that in the extruded state),resulting in a favorable strength-toughness ratio.Except for the nano-β'phase and semi-coherent Mg_(24)Y_(5) phase(mismatch=16.12%)around the grain boundaries,a small amount of nano-ZrO_(2) and Y_(2)O_(3) particles also play a role in dispersion strengthening.The high mechanical properties of the SLM state are chiefly attributed to precipitation hardening(44.41%),solid solution strengthening(34.06%)and grain boundary strengthening(21.53%),with precipitation hardening being predominantly driven by dislocation strengthening(67.77%).High-performance SLM Mg-RE alloy components were manufactured and showcased at TCT Asia 2024,receiving favorable attention.This work underscores the significant application potential of SLM Mg-RE alloys and establishes a strong foundation for advancing their use in the biomedical fields.
基金Project(22KJB430023)supported by the Natural Science Foundation for Colleges and Universities of Jiangsu Province,ChinaProject(1172922101)supported by the Youth Science and Technology Innovation Project of Jiangsu University of Science and Technology,China。
文摘The AlMgScZr high-strength aluminum alloy fabricated by selective laser melting(SLM)technology exhibits a“bimodal microstructure”,resulting in significant non-uniform deformation during thermal deformation.This study investigates the flow behavior of SLM-processed AlMgScZr aluminum alloy utilizing the Gleeble-1500D thermal simulation machine.The true stress-strain curves were amended based on the friction theory.Through determining the Zener-Hollomon parameters,the correlation between flow stress,deformation temperature,and strain rate during the high-temperature thermoplastic deformation of SLM-processed AlMgScZr aluminum alloy with a“bimodal microstructure”was established.In addition,the microstructural evolution during thermal deformation was analyzed.The results indicated that the predicted flow stress values obtained from the Arrhenius constitutive equation with coupled correction of thermal deformation parameters closely matched the experimental values.The correlation coefficient and the average absolute relative error of the corrected model were 0.999 and 2.766%,respectively,accurately predicting the thermoplastic deformation behavior of SLM-processed high-strength aluminum alloy with a“bimodal microstructure”.Furthermore,hot processing maps at different strains were established,identifying stable and unstable regions under different deformation conditions.Microstructural observations revealed different thermal deformation mechanisms under various deformation temperatures.Specifically,dynamic recrystallization characteristics dominated the microstructure at lower temperatures(300-360℃),while dynamic recovery was dominant at higher temperatures(390-500℃).
基金supported by the National Natural Science Foundation of China(NSFC)under Grant Nos.U24A2037,52130002,52321001.
文摘The effects of various heat treatments on the microstructures and mechanical properties of as-built selective laser melted Inconel 718 alloy were investigated through conventional and quasi-in-situ tensile tests.The corresponding heat treatment processes include direct aging(DA),solution+aging(SA),and homogenization+aging(HA).The DA and SA samples preserve the melt pool configuration and grain size stability,while the precipitated phase characteristics reveal the refinement of the long-strip Laves phase and the appearance of theδphase,respectively.The HA process induces recrystallization and grain coarsening.The specimens exhibit enhanced strength concomitant with diminished elongation,which is likely attributed to the reduction of the geometrically necessary dislocation density and the intensified precipitation of theγ′′phase after heat treatment.Tensile plastic deformation displays notable strain concentration along grain boundaries.The dimensional alterations in precipitated phases were measured to quantitatively determine the impact of grain boundary,dislocation and precipitation strengthening on the yield strength after heat treatment.Precipitation strengthening encompasses coherent,order,and Orowan strengthening.A remarkable agreement is revealed between theoretical predictions and experimental results.Insights are offered for optimizing heat treatment processes to comprehend microstructural evolution effect on the mechanical properties of additive-manufactured metals.
基金financially supported by the National Natural Science Foundation of China(No.12262014).
文摘A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructure and the mechanism of grain refinement in TA15 titanium alloy during SSP treatment.Transmission electron microscopyand Rietveld refinement methods were employed.The residual stress and microhardness variations with depth were also characterized.The results show:(1)At the initial stage of deformation,plastic deformation is primarily accommodated through twinning and dislocation slip.(2)As the strain increases,twinning disappears,and dislocations interact to form tangles.Some dislocations annihilate and rearrange into subgrain boundaries,subdividing the original grains into subgrains.(3)With continued dislocation activity,the subgrain size decreases until nanocrystals are formed through the dynamic rotational recrystallization.SSP introduced compressive residual stress(CRS)in the near-surface layer of the material,with the maximum CRS of approximately−1141 MPa observed in the subsurface layer.It also induced work hardening,increasing the surface hardness to approximately 479 HV.However,the surface roughness increases,leading to a slight deterioration in surface quality.
文摘In the original publication,mistakenly first and corresponding affiliation is given as:Thermoelectricity Technology Center,Hangzhou Dahe Thermo-Magnetics Co.Ltd,Hangzhou 310053,ChinaThe correct first and corresponding affiliation is:State Key Laboratory of Silicon Materials,School of Materials Science and Engineering,Zhejiang University,Hangzhou 310027,China.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3702501)the National Science and Technology Major Project(J2019-VI-0019-0134).
文摘Selective laser melting(SLM)has become a critical technique for manufacturing molds with conformal cooling channels to achieve high cooling efficiencies.A novel selective laser-melted 718HH plastic mold steel with an excellent combination of strength and toughness was investigated.After SLM fabrication,quenching and tempering are conducted as post-printing heat treatment(PPHT)to improve the mechanical properties of the as-built samples.Both the microstructure and the corresponding mechanical properties were systematically studied.The results show that PPHT facilitates the complete martensite transformation.Meanwhile,the retained austenite(γ)phase was still found in the as-built samples.And high-density dislocations were dispersively distributed within the martensite matrix for both as-built and as-PPHTed samples.After PPHT,due to the recovery and recrystallization of martensite,reduced dislocation density and increased high-angle grain boundaries,the microhardness of the as-built samples decreased from 498.8±16.7 to 382.1±5.0 HV0.3.Correspondingly,the strength,including the ultimate tensile strength and yield strength,of the as-built and as-PPHTed samples also decreased from 1411.3±17.8 to 1208.7±3.2 MPa and 1267.3±11.7 to 1084.7±5.1 MPa,respectively.On the contrary,the value of impact energy significantly increased from 15.3±1.2 J(as-built)to 39.7±1.2 J(as-PPHTed).Notably,the mechanical properties of SLMed 718HH samples are significantly better than those of corresponding wrought samples.
基金supported by the Pazy Foundation of the Israel Atomic Energy Commission and the Israeli Council of Higher Education(Grant No.322/20)。
文摘Only a few studies have reported the efects of electrochemical hydrogenation on the tensile mechanical properties of additively manufactured Ti–6Al–4V alloy,in all of them the alloy was processed by laser powder-bed fusion.Furthermore,the efects of either hot isostatic pressing(HIP)or heat treatment(HT)post-treatments on the mechanical properties were not reported.Here,the Young’s modulus,ultimate tensile stress,and uniform(homogeneous)strain of as-built electron beam melted(EBM)Ti–6Al–4V alloys were studied using small tensile specimens before and after electrochemical hydrogenation,as well as before and after secondary processes of HIP at 920℃ and HT at 1000℃.The tensile properties of all hydrogenated alloys were signifcantly degraded compared to their non-hydrogenated counterparts.The yield stress could not be determined for all hydrogenated alloys,as failure occurred at a strain below 0.2%ofset.The uniform strain of the hydrogenated alloys was less than 1%,compared to 1%–5%for the non-hydrogenated alloys.The fracture mode of the hydrogenated alloys after HIP and HT revealed cleavage fracture,indicating increased brittleness.In the as-built hydrogenated alloy,the fracture mode varied with location:brittle fracture occurred near the surface due to the formation of a hydride layer,while a more ductile fracture with dimples was observed below this layer.
基金supported by the National Natural Science Foundation of China(Nos.51801079,52001140)the National Funds Through FCT of Portugal–Fundacao para a Ciência e a Tecnologia,under a scientific contract of 2021.04115.CEECIND,and the Projects of UIDB/00285/2020,and LA/0112/2020。
文摘To improve the processability and mechanical properties of the selective laser melting(SLM)low Sc content Al−Mg−Sc−Zr alloy,Mn was used to partially replace Mg.The processability,microstructure,and mechanical properties of the SLM-fabricated Al−Mg−Mn−Sc−Zr alloy were systematically investigated by density measurement,microstructure characterization,and tensile testing.The results revealed that dense samples could be obtained by adjusting the SLM process parameters.The alloy exhibited a fine equiaxed-columnar bimodal grain microstructure.The presence of primary Al3Sc andα-Al(Mn,Fe)Si particles contributed to the grain refinement of the alloy with an average grain size of 4.63μm.Upon aging treatment at 350°C for 2 h,the strength and elongation of the alloy were simultaneously improved due to the precipitation of Al3Sc nanoparticles and the formation of the 9R phase.This study demonstrates that the strength−plasticity trade-off of the aluminum alloy can be overcome by utilizing SLM technology and subsequent post-heat treatment to induce the formation of the long-period stacked ordered phase.
基金provided by the NSERC Discovery grant # 341960-2013Canada Research Chairs Program to N.O. Scholarships to Erin Mann from NSERC CREATE and Memorial University of Newfoundland
文摘Mercury（Hg） in the Arctic is a significant concern due to its bioaccumulative and neurotoxic properties, and the sensitivity of Arctic environments. Previous research has found high levels of Hg in snowpacks with high chloride（Cl-） concentrations. We hypothesised that Cl- would increase Hg retention by decreasing Hg photoreduction to Hg（0） in melted Arctic snow. To test this, changes in Hg photoreduction kinetics in melted Alert, NU snow were quantified with changing Cl- concentration and UV intensity. Snow was collected and melted in Teflon bottles in May 2014, spiked with 0–10 μg/g Cl-, and irradiated with 3.52–5.78 W·m-2 UV（280–400 nm）radiation in a Luz Chem photoreactor. Photoreduction rate constants（k）（0.14–0.59 hr-1） had positive linear relationships with [Cl-], while photoreduced Hg amounts（Hg（Ⅱ）red） had negative linear relationships with [Cl-]（1287–64 pg in 200 g melted snow）. Varying UV and[Cl-] both altered Hg（Ⅱ）red amounts, with more efficient Hg stabilisation by Cl- at higher UV intensity, while k can be predicted by Cl- concentration and/or UV intensity, depending on experimental parameters. Overall, with future projections for greater snowpack Cl- loading,our experimental results suggest that more Hg could be delivered to Arctic aquatic ecosystems by melted snow（smaller Hg（Ⅱ）red expected）, but the Hg in the melted snow that is photoreduced may do so more quickly（larger k expected）.
基金The author would like to acknowledge the support by the National Natural Science Foundation of China (Grant No. 50105006)and the support by the 985 Foundation of Tsinghua University,Beijing, China.
文摘To develop large-scale RP systems used to producing functional parts and large-sized models has become an urgentcall now. In this paper, a large-scale RP system, MEM600-l, based on the melted extrusion manufacturing (MEM)process has been developed successfully. And the key issues to develop such a system are discussed. Based on theactual forming experiment, it is concluded that the MEM600-l works reliably and the forming efficiency is muchhigher than its parallel equipments.
文摘The characteristics of some elements in inoculant were analyzed.The effect of the morphology of instantaneous inoculant on its melting velocity was studied.When the inoculants pass through the same sieve number,the volume and the ratio of surface area to volume are different.It is evident from the theoretical analysis and experiment under some conditions that the melting velocity of inoculant depends on the morphology of inoculant.The morphology of inoculant during production should be controlled carefully.
基金supported financially by the National Key Research and Development Program of China (No. 2017YFB 0702300)the National Natural Science Foundation of China (No. 51671029)the Fundamental Research Funds for the Central Universities (No. FRF-TP-17-002B)
文摘Irregular grains, high interfacial stresses and anisotropic properties widely exist in 3D-printed metallic materials, and this paper investigated the effects of heat treatment on the microstructural, mechanical and corrosion properties of 316 L stainless steel fabricated by selective laser melting. Sub-grains and low-angle boundaries exist in the as-received selective laser melted(SLMed) 316 L stainless steel. After heat treatment at 1050℃, the sub-grains and low-angle boundaries changed slightly, and the stress state and strength decreased to some extent due to the decrease of dislocation density. After heat treatment at 1200℃, the grains became uniform, and the dislocation cells vanished, which led to a sharp decline in the hardness and strength. However, the ductility was improved after recrystallization heat treatment.The passive film thickness and corrosion potential of the SLMed 316 L stainless steel decreased after heat treatment, and the pitting potential also decreased due to the accelerated transition from metastable to steady-state pitting;this accelerated transition was caused by the presence of weak passive films at the enlarged pores after heat treatment, especially for an adequate solid solution treatment.
基金supported financially by the Pre-research Fund Project of Ministry of Equipment and Development of China (No. 61409230301)the Fundamental Research Funds for the Central Universities (No. HUST: 2016YXZD005)+1 种基金the National Natural Science Foundation of China (No. 51805186)the China Postdoctoral Science Foundation Funded Project (Nos. 2017M620317 and 2018T110759)
文摘Laser welding is a promising process for joining small components produced by selective laser melting (SLM) to fabricate the large-scale and complex-shaped parts. In the work, the morphology, microstructure, microhardness, tensile properties and corrosion resistance of the laser welded stress-relieved SLMed 304 stainless steel joints are investigated, as the different sections of stress-relieved SLMed 304 stainless steel are joined. Results show that the SLMed 304 stainless steel plates have a good laser weldability. The microstructure of laser-welded joints consists of the cellular dendrites in austenite matrix within columnar grains, exhibiting a coarser dendrite structure, lower microhardness (~220HV) and tensile properties (tensile strength of ~750 MPa, and area reduction of ~27.6%), but superior corrosion resistance to those of SLMed plates. The dendrite arm spacing of the joints varies from ~3.7μm in center zone, to ~5.0 (xm in fusion zone, to ~2.5 in epitaxial zone. The SLMed anisotropy shows a negligible effect on the microstructure and performance of the laser-welded joints. The laser welding along the building directions of the SLMed base plates can induce a slightly finer dendritic structure and higher tensile properties.
基金the financial support from the National Key Research and Development Program of China(No.2018YFB1106400)。
文摘Finite element modeling(FEM),microscopy,X-ray computed tomography(CT)and mechanical property tests were used to study the microstructure,porosity and mechanical properties of an AlSi10Mg alloy produced by selective laser melting(SLM).The simulation of the melt pool and thermal history under different energy densities produced an optimized result with an energy density of 44.5 J·mm-3.The high cooling rate during the SLM process significantly refined the previous a-Al dendrites.The growth direction of the network-like Al-Si eutectic structure at different orientations confirmed the anisotropic nature of the microstructure.Furthermore,the microhardness,tensile testing and fracture analysis results proved that there were no obvious distinctions in the strength between the transverse and longitudinal directions,and that the ductility was anisotropic,possibly due to the shape and distribution of the pores.The pores measured by X-ray CT at different energy densities confirmed that the sphericity of the pores was inversely related to pores volumes.With optimized processing conditions,the porosity of the selective laser melted sample decreased leading to the improved fabricated fuel system component via SLM.
基金supported financially by the National Key Research and Development Programme of China(Nos.2016YFB1100602 and 2016YFB1100100)。
文摘In this study,the microstructure and tensile properties of selective laser melted AlSilOMg at elevated temperature were investigated with focus on the interfacial region.In-situ SEM and in-situ EBSD analysis were proposed to characterize the microstructural evolution with temperature.The as-fabricated AlSilOMg sample presents high tensile strength with the ultimate tensile strength(UTS)of~450 MPa and yield strength(YS)of~300 MPa,which results from the mixed strengthening mechanism among grain boundary,solid solution,dislocation and Orowan looping mechanism.When holding at the temperature below 200℃for 30 min,the micro structure presents little change,and only a slight decrement of yield strength appears due to the relief of the residual stress.However,when the holding temperature further increases to 300℃and 400℃,the coarsening and precipitation of Si particles inα-Al matrix occur obviously,which leads to an obvious decrease of solid solution strength.At the same time,matrix softening and the weakness of dislocation strengthening also play important roles.When the holding temperature reaches to 400℃,the yield strength decreases significantly to about 25 MPa which is very similar to the as-cast Al alloy.This might be concluded that the YS is dominated by the matrix materials.Because the softening mechanism counteracts work hardening,the extremely high elongation occurs.
基金the financial support from the National Natural Science Foundation of China [51805415,51922048]China Postdoctoral Science Foundation [2019M663682]+2 种基金China Postdoctoral Science Foundation [Grant number 2019M663682]Young Elite Scientists Sponsorship Program by CAST [Grant number 2021QNRC001]the fund of State Key Laboratory of Long-life High Temperature Materials (DECSKL202104)。
文摘In the context of global carbon neutrality, the application of lightweight magnesium alloys is becoming increasingly attractive. In this study, selective laser melting(SLM) was employed to achieve nearly full dense and crack-free AZ91D components with fine equiaxed grain structure. The formation mechanism of typical pore defects(gas pore, lack-of-fusion pore and keyhole pore) and melting modes(keyhole mode and conduction mode) were systematically studied by varying the laser power and scanning speed. The morphology and volume fraction of the pores under different processing conditions were characterized. A criterion based on the depth-to-width ratio of the melt pool was established to identify different melting modes. The strength and ductility(tensile strength up to 340 MPa and uniform elongation of 8.9%)of the as deposited AZ91D are far superior to those of the casting components and are comparable to those of its wrought counterparts.The superior balance of strength and ductility of SLMed AZ91D, as well as the negligible anisotropic properties are mainly ascribed to the extremely fine equiaxed grain structure(with average grain size of ~1.2 μm), as well as the discontinuous distribution of β-Al_(12)Mg_(17) phases. It thus provides an alternative way to fabricate high-strength magnesium alloys with complex geometry.
基金supported by the National Natural Science Foundation of China (Nos. 61534001 and 11574267)the National Science Fund for Distinguished Young Scholars (No.51725102)
文摘For zone-melted （ZM） bismuth telluride-based alloys, which are widely commercially available for solidstate cooling and low-temperature power generation around room temperature, introducing point defects is the chief approach to improve their thermoelectric performance. Herein, we report the multiple effects of Se doping on thermoelectric performance of p-type Bi0.5Sb1,5Te3-xSex ＋ 3 wt% Te ZM ingots, which increases carrier concentration, reduces lattice thermal conductivity and deteriorates the carrier mobility. As a result, the peak figure of merit （ZT） is shifted to a higher temperature and a high ZT 1.2 at 350 K is obtained, due to the reduced thermal conductivity and suppressed intrinsic conduction. Further, decreasing Sb content is followed to optimize the room temperature performance and a ZT - 1.1 at 300 K is obtained. These results are significant for designing and optimizing the thermoelectric performance of commercial Bi0.5Sb1.5Te3＋ 3 wt% Te ZM alloys.
基金supported financially by the Shanghai Science and Technology Committee Innovation Grant (Nos. 17JC1400600 and 17JC1400603)Distinguished Professor Program of Shanghai University of Engineering Science。
文摘This work characterizes microstructural evolutions of electron beam melted(EBM) Ti-6 Al-4 V alloy modified via laser shock peening(LSP).The depth stress distribution and tensile properties of EBM Ti-6 Al-4 V alloy were measured before and after LSP.The results indicate that microstructure consists of β phase with 7.2%±0.4% vol.% and balance α lamellar in EBM sample,and the α lamella was refined into nano-equiaxed grains and submicro-equiaxed grains after LSP.The dominant refinement mechanism is revealed during LSP.Stacking faults were found in the LSP-treated sample,and their corresponding planes were determined as(0001) basal plane,(1010) prismatic plane,and(1011) pyramidal plane obtained by high resolution transmission electron microscopy.The subgrains and high-angle grains formed during dynamic recrystallization were identified by selected area electron diffraction pattern.The LSP treatment produces a significantly residual compressive stress approximately-380 MPa with the depth of compressive stress layer reaching 450 μm.Strength and elongation of the EBM sample were significantly increased after LSP.The strength and ductility enhancements are attributed to compre s sive stress,grain refinement and grain gradient distribution of α phase.
基金support of the ECU Postgraduate Research AwardForrest Research Foundation Ph D Scholarship+1 种基金the Australian Government Research Training Program Scholarship(ECU)the facilities,and the scientific and technical assistance of the Australian Microscopy&Microanalysis Research Facility at the Centre for Microscopy,Characterisation&Analysis,The University of Western Australia,a facility funded by the University,State and Commonwealth Governments。
文摘Although using elemental powder mixtures may provide broad alloy selection at low cost for selective laser melting(SLM), there is still a concern on the resultant microstructural and chemical homogeneity of the produced parts. Hence, this work investigates the microstructure and mechanical properties of a SLM-produced Ti-35 Nb composite(in wt%) using elemental powder. The microstructural characteristics including ? phase, undissolved Nb particles and chemical homogeneity were detailed investigated.Nanoindentation revealed the presence of relatively soft undissolved Nb particles and weak interface bonding around Nb-rich regions in as-SLMed samples. Solid-solution treatment can not only improve chemical homogeneity but also enhance bonding through grain boundary strengthening, resulting in43 % increase in tensile elongation for the heat-treated Ti-35 Nb compared to the as-SLMed counterpart. The analyses of tensile fractures and shear bands further confirmed the correlation between the different phases and the ductility of Ti-35 Nb. In particular, the weak bonding between undissolved Nb and the matrix in the as-SLMed sample reduces its ductility while the ? grains in solid-solution treated Ti-Nb alloy can induce a relatively stable plastic flow therefore better ductility. This work sheds insight into the understanding of homogenization of microstructure and phases of SLM-produced alloys from an elemental powder mixture.
基金financially supported by the National Natural Science Foundation of China(No.51801198)the National Key R&D Plan(No.2016YFC1100502).
文摘In this study,the CoCrW-x Cu alloys(x=2,3 and 4 wt%)were fabricated using selective laser melting(abbreviated as Co-2 Cu,Co-3 Cu and Co-4Cu)with the purpose of reducing the inflammation responses and the activity of osteoclast.The metal ions releasing test showed that when the Cu content was less than 4 wt%,the releasing amount of Co and Cr ions was very small;however,when 4 wt%Cu was added in the CoCrW based alloy,the quantity of Co ions was significantly elevated with respect to the other groups due to the segregation of precipitates in the matrix;the Cu2+ion quantity of the Co-2Cu,Co-3Cu and Co-4Cu alloys were 0.05,0.09 and 0.27 g/(L cm2)after 7 d immersion,respectively;the RT-q PCR and ELISA data indicated that the expression levels of the pro-inflammatory cytokines(TNF-αand IL-6)were down-regulated in the Co-3Cu and Co-4Cu groups,whereas the expression level of the anti-inflammatory cytokine(IL-10)was up-regulated in all CoCrW-x Cu alloys;meanwhile,the Cu-containing CoCrW alloys significantly down-regulated the expression of the NF-B signal pathway in a Cu content-dependent manner,and the downstream transcription factors of NF-B signal pathway including NFATc1,TRAP and Cath-K were also down-regulated via potentially manipulating the NF-B signal pathway.After comprehensive consideration,it is considered that the Co-3Cu alloy is a potential material for self-alleviating inflammatory responses.
