Muhammad Ali SiddiquiIhsan UllahHui LiuShuyuan Zhang...
117-127页
查看更多>>摘要：The adsorption behavior,antibacterial,and corrosion properties of a Ti-3Cu alloy were studied in a phosphate-buffered saline solution containing 0,1,3,and 6 g L-1 bovine serum albumin protein at 37 ℃and pH =7.4 (±0.2).The protein adsorption behavior was examined via cyclic voltammetry,secondary ions mass spectroscopy (SIMS),and angle-resolved X-ray photoelectron spectroscopy (ARXPS).The cor-rosion property was analyzed by the open circuit potential (OCP),potentiodynamic polarization (PD),and electrochemical impedance spectroscopy (EIS) examinations.The antibacterial test was conducted according to the GB/T 21510 China Standard.It was observed that the surface charge density (Q～s) was directly proportional to the amount of the adsorbed BSA protein,signifying that the protein adsorption was accompanied by the charge transfer,pointing to chemisorptions phenomena.BSA amino groups and other organic species were observed in the surface analysis examinations.It was shown that the formation of barrier complexes between the TiO2 oxide-layer and PBS solution resulted in decreasing the release of Cu-ions,which consequently reduced the antibacterial activity.On the other hand,these barrier complexes improved the corrosion resistance by increasing the charge transfer resistance and double-layer capacitance of the Ti-3Cu alloy.
查看更多>>摘要：Nickel metal hydride (Ni-MH) rechargeable batteries hold an important position in the new-energy vehicle market owing to their key technology advantages.Their negative electrode materials-hydrogen storage alloys (HSAs) are always on the spotlight and are the key to compete with the burgeoning Li-ion batteries.Here,for the first time we report a series of biphase supperlattice HSAs with a (La,Mg)2Ni7 matrix phase and anovel (La,Mg)7Ni23 secondary phase.The biphase alloys show discharge capacities of 402-413 mAh g-1 compared with 376-397 mAh g-1 of the other multi-or single-phase alloys.These val-ues are among the highest for superlattice HSAs.In addition,the alloy with 15.4 wt.％ (La,Mg)7Ni23 phase exhibits good high rate dischargeability due to the proper compromise between the amount of crystal boundaries and equilibrium plateau voltage.The cycling stability of the biphase alloys is lower than that of the single-phase alloy but is till higher than the multiphase alloy.The novel superlattice biphase alloys with superior overall electrochemical properties are expected to inspire further design and development of HSAs as advanced electrode materials for power batteries.
查看更多>>摘要：The alloying effects of Ni,W and Cr on the microstructural stability of CoNi-base alloys were investigated using a multicomponent diffusion multiple after being aged at 1000 ℃ for 1000 h.The diffusion multiple was carefully designed based on thermodynamic calculations.The relationships between alloy compo-sitions and microstructural characteristics were established over a large compositional range using this single sample,and the alloying effects of Ni,W and Cr on the elemental partitioning behaviors between γ and γ'two phases were thermodynamically analyzed using high-throughput calculation.The results together show that an increase of Ni content increases the γ'volume faction in the long-term aged microstructures.However,the higher Ni content leads to the precipitation of the x phase by promoting the partitioning of W from the γ'phase to the γphase.The decrease of W content dramatically reduces the γ'volume faction,but the addition of Cr can properly counteract this effect by promoting the partitioning of Al and Ti from the γphase to the γ'phase.This study will be helpful for accelerating the development of novel γ'-strengthened multicomponent CoNi-base alloys,as well as providing experimental data to improve the thermodynamic database.
查看更多>>摘要：In the present work,a double-pass continuous expansion extrusion forming (CEEF) process was proposed for an Al-Mg-Si alloy,in which the diameter of rods was gradually expanded.The microstruc-tural evolution,mechanical properties and deformation characteristics were investigated by utilizing microstructural observations,mechanical testing and a finite element method coupled with a cellular automata model.The results showed that the strength and ductility of the double-pass CEEF processed Al-Mg-Si alloys were improved synchronously,especially in artificially aged alloys.The grain size of the processed Al-Mg-Si alloy rods was refined remarkably by continuous dynamic recrystallization (CDRX)and geometric dynamic recrystallization (GDRX),and the homogeneity of microstructure was gradu-ally improved with increasing number of processing passes.The artificially aged alloy processed with double-pass CEEF and water quenching contained fine (sub)grains and high-density dislocations,which resulted in more needle-shaped β" precipitates and a larger precipitate aspect ratio than the as-received and air-cooled CEEF alloys owing to the different precipitation kinetics.The severe cumulate strain and microshear bands were found to accelerate CDRX and GDRX for grain refinement between adjacent posi-tions of the parabolic metal flow due to the special temperature characteristics and large shear straining during the CEEF process.
查看更多>>摘要：The ω phase is commonly observed in β-Ti alloys and plays a significant role on various properties of β-Ti alloys.Although many results about the role ofω phase on mechanical properties of β-Ti alloys have been derived from theoretical and experimental studies,the role ofω phase on deformation mechanism hitherto remains elusive and deserves to be further studied.In this work,the role played by ω phase during the {112 } <111>β twinning in Ti-Mo alloys were investigated by first-principles calculations at atomic scale.In the energy favorable interface of(112)β/(10(1)0)ω,we found that partial dislocations slipping on the successive (10(1)0)ω planes ofω phase can lead to the formation of { 112} <111>β twin nucleus.And the twin nucleus grows inwards ω grain interior through atomic shuffle.Thus,a new twinning mechanism of {112 } <111>β assisted by ω phase was proposed.Furthermore,our calculations indicated that the Pearance of ITB (interfacial twin boundary) ω phase can improve the stability of the symmetrical 12 } <111 >β twin boundary (TB),which can well explain the experimental phenomenon that the ITB ω phase always accompanies the formation of {112 } <111>β twin.Finally,a probable microstructure evolution sequence was suggested,namely β matrix → β matrix + athermal ω phase → (112)[11(1)]twin → (112)[11(1)]β twin + ITB ω phase.Our calculations provide new insights on the role played by ω phase during the twinning process of {112} <111>β,which can deepen the understanding on the deformation behaviors of β-Ti alloys.
查看更多>>摘要：TiO2 (B) nanosheets/GO (graphene oxide) hybrids are considered to be outstanding performance pho-tocatalysts for high efficiency of H2 evolution.However,they still suffer severe challenges during the synthetic processes,such as a large amount of the capping agents adhering on the surface and easy occurrence of aggregation.To figure out these obstacles,Ar plasma treatment as a modified method in this study not only enable the TiO2 (B) nanosheets distributed uniformly on the GO sheets but also engi-neer defects within TiO2 (B) nanosheetsto significantly improve the photocatalytic activity for the water splitting.The hydrogen evolution rate of the TiO2-x (B)/GO sheets is 1.4 times higher compared with that of original TiO2 (B)/GO sheets without Ar plasma treatment.The improved photocatalytic proper-ties were owing to the synergetic effects of oxygen vacancies and the heterojunction between GO and TiO2 (B),which can promote the visible light utilization and accelerate separation and transportation of photogenerated electron-holes.This study can provide a facile pathway to prepare the two-dimensional hybrid photocatalysts with high photocatalytic H2 activity.
查看更多>>摘要：Severe erosion by hard particles is a crucial problem to engine blades when aircraft take off and land in harsh environments,especially for the developed lightweight titanium alloy components.Here,we deposited the Ti/TiAlN multilayer coatings with various cycles on Ti-6Al-4V substrates by a home-made hybrid multisource cathodic arc system.The effects of the silica sand and glass beads on erosion behavior of the coatings were focused.Results showed that the Ti/TiAlN multilayer coatings eroded by the silica sand exhibited the predominant "layer by layer" failure mechanism.In particular,increasing the number of cycles led to the dramatic increase in erosion rate for Ti/TiAlN multilayer coatings,due to the deterio-ration of their mechanical properties.Different from the silica sand case,however,the erosion rate of the coatings treated by glass beads indicated faint dependence upon the number of cycles,where the coating failure was dominated by the "piece by piece" failure mechanism.Noted that the Ti layers along with the formed interfaces enhanced the erosion resistance of the coatings,although the failure mechanisms were differently eroded by silica sand and glass beads.Meanwhile,the Ti layers and interfaces hindered the propagation of radial cracks and restrained the lateral cracks within one single TiAlN layer.
查看更多>>摘要：This work aims at understanding the features of the Sn grains from which whiskers preferentially grow.The growth behavior of Sn whiskers on a 50 μm thick hypereutectic Sn-Al alloy coating was observed in situ by mapping the grain orientations before and after aging using the electron backscatter diffraction(EBSD) technique.Sn whiskers were found to grow preferentially from the (001) or near-(001) grains sur-rounded by the grains having perpendicular orientations,such as (100),(110) and (210).The compressive stress in the coating was heterogeneous,and the (001) grains exhibited the higher compressive stress close to the grain boundaries.The orientation relationship between α-Al phase and β-Sn phase was con-firmed as (200)α-Al || (200)β-Sn,[01(1)]α-Al ||[001]β-Sn.The plane matching resulted in approximately 0.7 ％ misfit strain in β-Sn,which had little impact on the growth of whiskers.Dislocations pile-ups were found in the (001) grains and repulsed by the Sn oxide layer,giving the probability of cracking the oxide.Grain boundaries were found between the whisker and underneath grain.The dominant diffusion mode for early whisker growth was grain boundary diffusion aided by pipe diffusion.
查看更多>>摘要：In recent years,the Ti2AlNb-based alloys are selected as potential alloys for elevated temperature appli-cations to replace conventional Ni-based superalloys owing to their good creep resistance and oxidation resistance which are related to the O precipitates.In this paper,the precipitation mechanisms of O phase,phase transformation and microstructure control of Ti2AlNb-based alloys are reviewed.Ti2AlNb-based alloys generally consist of B2/β,α2,and O phase with different morphologies which are derived from the various heat treatment processes,including equiaxed α2/O particles,bimodal microstructure,and Wid-mannst(a)tten B2/β + O structures etc.As a newly developed strengthening phase,O precipitates can be precipitated from the B2/β matrix or α2 phase directly as well as generated by means of peritectoid reac-tion ofα2 phase and bcc matrix.Microstructural control of the Ti2AlNb-based alloys can be implemented by refining the original B2/β grain size and regulating the O precipitates.Multidirectional isothermal forging (MIF) and powder metallurgy technique are two effective methods to refine the original B2/β grains and the morphology and size of O precipitates can be regulated by adding alloying components and pre-deformation process.Moreover,the phase diagram as well as coarsening behavior of Ti2AlNb-based alloys in ageing process is also reviewed.For the further application of these alloys,more emphasis should be paid on the deep interpolation of microstructure-property relationship and the adoption of advanced manufacturing technology.
查看更多>>摘要：In the past decade,the sudden rise of high-entropy alloys (HEAs) has become a research hotspot in the domain of metal materials.HEAs break through the design concept of traditional single-principal element alloys,and the four core effects,especially the high entropy and cocktail effects,make HEAs exhibit much better corrosion resistance than traditional corrosion-resistant metal materials,e.g.,stain-less steels,copper-nickel alloys,and high-nickel alloys.Currently,the corrosion resistance of HEAs causes great concern in the field of corrosion research.This article reviews the corrosion behavior and mechanism of HEAs in various aqueous solutions,revealing the correlation among the composition,microstructure and corrosion resistance of HEAs,and elaborates the influence of heat treatment,anodizing treatment and preparation methods on the corrosion behavior of HEAs.This knowledge will benefit the on-demand design of corrosion-resistant HEAs,which is an important trend of future development.Finally,perspec-tives regarding the corrosion research of HEAs are outlined to guide future studies.
NETL
NSTL
维普
万方数据