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| 1 | Unveiling anneal hardening in dilute Al-doped Al_(x)CoCrFeMnNi(x = 0,0.1) high-entropy alloys显示文摘Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature(T_(rx)).Microscopically,this hardening effect has been ascribed to several mechanisms,i.e.solute segregation to defects(dislocation and stacking fault) and short-range chemical ordering,etc.However,none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys(HEAs).Here we report the observations,using high-resolution electron channeling contrast imaging and transmission electron microscopy,of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T_(rx).The dislocation substructures are observed to be thermally stable up to T_(rx),which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation occurs.The microstructure feature is markedly different from that of conventional dilute solid solution alloys,in which dislocation substructures gradually vanish by recovery during annealing,leading to a strength drop.Furthermore,dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed(≤500℃) HEA.This Al induced softening effect,could be associated with the anisotropic formation of dislocation substructure,resulting from enhanced dislocation planar slip due to glide plane softening effect.These findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening. | Q.Cheng X.D.Xu P.Xie L.L.Han J.Y.He X.Q.Li J.Zhang Z.T.Li Y.P.Li B.Liu T.G.Nieh M.W.Chen J.H.Chen | 2021 | Journal of Materials Science & Technology2021，，32： | 3 |
| 2 | Electron tomography for sintered ceramic materials by a neural network algebraic reconstruction technique显示文摘The missing wedge effect in electron tomography introduces various types of artifacts in the tomograms and lowers the reconstruction resolution and quality.The artifacts produced in tomographic reconstruction of bulk materials can be very severe,particularly for sintered bulk ceramic materials in which there are often nano-pores or pore-like microstructure features.Here,we report a neural network algebraic reconstruction algorithm with no prior knowledge to perform electron tomography for a sintered SiC material with nano carbon zones.The results show that the proposed algorithm has a great suppressive effect on the missing wedge artifacts and a high tolerance for noise.The information in the missing wedge can be partly recovered by this technique.Thus,both the shape of the bulk SiC specimen and its irregular inner pore-like features are correctly retrieved in the obtained 3D image.Our study shows the effectiveness of the neural network algorithm for improving the reconstruction accuracy of electron tomography,in order to reveal sophisticated 3D microstructures generally existing in sintered ceramic materials. | R.H.Shen Y.T.He W.Q.Ming Y.Zhang X.D.Xu J.H.Chen | 2022 | Journal of Materials Science & Technology2022，，5： | 2 |
| 3 | Effect of friction on corrosion behaviors of AISI 304 and Cr26Mo1 stainless steels in different solutions显示文摘The corrosion and tribocorrosion behaviors of AISI 304 austenitic stainless steel and Cr26Mo1 ultrapure high chromium ferrite stainless steel in 3.5 wt.%NaCl and 0.5 mol/L H2SO4 solutions were investigated.Microelectrode electrochemical measurement technology was applied to identify electrochemistry behaviors during tribocorrosion tests in situ.The surface morphologies and compositions of the wear tracks were analyzed by scanning electron microscopy and Raman spectrum.The results showed that compositions of stainless steels,corrosive mediums and applied loads have great influence on tribocorrosion behaviors of stainless steels.Firstly,the corrosion resistance in static state of stainless steels primarily dominates its tribocorrosion behavior;meanwhile,better mechanical properties are in favor of tribocorrosion resistance.Secondly,the corrosion rate is promoted significantly in 3.5%NaCl solution by friction,while the tendency is inconspicuous in 0.5 mol/L H2SO4 solution.Last but not least,passive films on stainless steels can be wiped off by small friction force.With the increase in applied load,the effect of friction converts to forming friction oxide film from removing passivation film,so that a critical load exists below which the friction force can promote the corrosion process extremely. | Z.X.Dai S.L.Jiang L.K.Ning X.D.Xu S.Li D.L.Duan | 2023 | Journal of Iron and Steel Research(International)2023，30，12： | 0 |
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