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A Study on Corrosion Behavior of Cr-Al-N Coatings Deposited by Reactive Magnetron Sputtering

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A Study on Corrosion Behavior of Cr-Al-N Coatings Deposited ...

An Examination on Atomic-level Stress Calculations by Nanoindentation Simulation via the Quasicontinuum Method

Fifth International Conference on Surface Engineering

作者： Shuwang Duo1 Ming Zhu2 Meishuan Li3 1 Jiangxi Key laboratory of Surface Engineering Jiangxi Normal University of science & Technology Nanchang 330013 china 2 Dept.of Material science and Engineering Xi’an University of science & Technology Xi’an 710054 china 3 shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of sciences shenyang 110016 china

CrN and Cr-Al-N coatings were deposited on glass substrate and the corrosion behavior of them was *** electrochemical tests using both DC（polarization curves） and AC techniques（EIS） were carried out on Potentiostat/Galvanstat（EG＆G） in the 3.5 wt% NaCl *** surface morphologies of the Cr-Al-N coatings with different aluminum content after corrosion tests were no obvious differentiations of the morphologies between pre-corrosion and after-corrosion except that spallation was observed on the surface of the CrN *** being immersed into NaCl solution for 1 hour,the mass of the coating kept constant with the time *** can be explained by the passivation of the *** comparison between Ecorr for the Cr-Al-N coatings with different aluminum content revealed that the corrosion potentials for the aluminum contain coatings were nobler than that for CrN *** meant that the addition of aluminum shifted Ecorr to more positive potential *** these coatings,CrN in NaCl solution exhibited the worst corrosion resistance,while the corrosion resistance of Cr0.63Al0.37N in NaCl solution was the *** polarization data and EIS data suggest that addition of aluminum can improve the corrosion resistance of CrN coating.

关键词： Magnetron sputtering Cr-Al-N coatings Corrosion behavior

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Journal of materials science & Technology 2010年第1期26卷 56-64页

作者： Yufei Shao and Shaoqing Wang shenyang national laboratory for materials science, Institute of Metal Research, Chinese Academy of sciences, shenyang 110016, china [a] shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of sciences shenyang 110016 china

Nanoindentation simulations on single crystals AI and Cu via the quasicontinuum method have been performed. Two kinds of atomic-level local stress calculation methods, i.e. the coarse-grained local stress and the virial local stress, are employed to calculate the stress state of the contact area. Various comparisons between the coarse-grained local stress and the virial local stress have been made. Firstly, the averaged normal stress beneath the contact surface calculated by coarse-grained method agrees well with continuum mechanical pressure measurement, while the virial method gives unphysical results sometimes. Secondly, the coarsegrained results reflect the indenter size effect on the critical shear stress quite accurately, while the virial calculations fail. Thirdly, the distribution of maximum shear stress of the coarse-grained method predicts the defects nucleation locations reliably, while the distribution of virial local stress gives an incorrect prediction sometimes. Thus it is concluded that the coarse-grained method can offer a more reliable description of the local stress states of atoms in spatially inhomogeneous solids.

关键词： Nanoindentation Atomistic stress Quasicontinuum

Vibration Effects on the Structural Stability of Al-Ti Intermetallics by First-principles Calculations

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Journal of materials science & Technology 2010年第12期26卷 1071-1077页

作者： Hui Zhang and Shaoqing Wang shenyang national laboratory for materials science,Institute of Metal Research,Chinese Academy of sciences,shenyang 110016,china [a] shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of sciences shenyang 110016 china

The structural stability of the intermetallics AlTi3, Al2Ti, Al3Ti4 and Al3Ti in the Al-Ti system has been investigated using density functional theory （DFT） and density functional perturbation theory （DFPT）. The calculated ground-state convex hull is in agreement with the experimental researches. Al3Ti4 （hP7） is metastable at 0 K and may be stabilized as the temperature increases due to the effects of the vibration entropy. For Al2Ti, r-Al2Ti is stable at 0 K and h-Al2Ti is stabilized by the vibration entropy at high temperatures. Al3Ti （tI16） is unstable considering vibration effects and Al3Ti （tI8） is the most stable structure at 0 K.

关键词： First-principles Al-Ti Vibration Crystal structure

Strain-induced Microstructure Refinement in a Tool Steel Subjected to Surface Mechanical Attrition Treatment

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Journal of materials science & Technology 2010年第3期26卷 258-263页

作者： Shoudan Lu,Zhenbo Wang and Ke Lu shenyang national laboratory for materials science,Institute of Metal Research,Chinese Academy of sciences,shenyang 110016,china [a] shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of sciences shenyang 110016 china

A nanostructured surface layer has been fabricated on an AISI H13 tool steel by means of surface mechanical attrition treatment （SMAT）.Strain-induced refinement processes of ferrite grains and carbide particles have been investigated by transmission electron microscopy （TEM） and scanning electron microscopy （SEM） in the SMAT surface *** refinement of ferrite is found to be dominated by dislocation activities and greatly facilitated by a large number of carbide particles at a depth 〉20 μ*** comparisons with microstructure refinement processes in other SMAT ferrite steels indicate that a larger volume fraction of carbide particles with a lower shear strength is expected to facilitate the refinement process of ferrite grains.

关键词： Nanostructured and nanocrystalline material AISI H13 tool steel Grain refinement Surface mechanical attrition treatment (SMAT) Carbides

A Novel Deflection Method for Measuring the Growth Stress of Thermally Growing Oxide Scales

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Journal of materials science & Technology 2003年第3期19卷 231-234页

作者： Yuhai QIAN Meishuanshenyang national laboratory for materials science, Institute of Metal Research, Chinese Academy of sciences, shenyang 110016, china Lab. for Mat. Sci. Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

A kind of new deflection technique has been developed for measuring the growth stress of thermally growing oxide scales during high temperature oxidation of alloys. The average growth stresses in oxide scales such as Al2O3, NiO and Cr2O3 formed on the surface of the superalloys can be investigated by this technique. Unlike the comventional deflection method, the novel method does not need to apply a coating for preventing one main face of thin strip specimen from oxidizing and can be used under the condition of longer time and higher temperature.

关键词： Oxide film Growth stress Deflection method

Microstructure Investigation on the Triple Junction with an Adjoining Twin Boundary in Nanocrystalline Palladium

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Journal of materials science & Technology 2010年第11期26卷 1047-1050页

作者： Yuchen Wang,Zhenxing Su and Dehai Ping shenyang national laboratory for materials science,Institute of Metal Research,Chinese Academy of sciences,shenyang 110016,china [a] shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of sciences shenyang 110016 china

By using high-resolution transmission electron microscopy,a [110] triple junction （TJ） containing a twin boundary （TB） in nanocrystalline palladium has been observed along the common axis *** statics calculation and imaging simulation were performed to determine the atomic structure of the *** modeling structure exhibits that the adjoining TB is a distorted one,whilst other two adjoining grain boundaries （GBs） exist in steady equilibrium *** present observation gives a clear example demonstrating that the adjoining TB can release the larger stresses residing at the junction.

关键词： Triple junction Grain boundary Molecular statics High-resolution transmission electron microscopy (HRTEM)

Transformation Behavior of Precipitates in a W-alloyed 10 wt pct Cr Steel for Ultra-supercritical Power Plants

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Journal of materials science & Technology 2010年第9期26卷 817-822页

作者： Xiaoqiang Hu,Namin Xiao,Xinghong Luo and Dianzhong Li shenyang national laboratory for materials science,Institute of Metal Research,Chinese Academy of sciences,shenyang 110016,china [a]shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Thermodynamic calculation,thermal analysis,and identification and observation of precipitates have been carried out on a W-alloyed 10 wt pct Cr steel by means of ThermoCalc program,differential thermal analysis（DTA）,X-ray diffraction（XRD） and transmission electron microscopy（TEM） with an energy dispersive Xray spectrometer,*** critical phase transformation points were determined by combining experimental results with *** individually stable phases of Nb（C,N） and VN,instead of one single phase MX（X：C,N）,M23C6 or Laves phases,were predicted in the calculated equilibrium phase *** unstable elongated M7C3 with relatively higher Cr was detected unexpectedly in the normalized and tempered *** kinds of spherical Nb（C,N） with different size were recognized as the primary and the secondary precipitates of Nb（C,N） which contain different V *** was observed that one kind of complex precipitate in a special V-wing shape was resulted from two plate-like VN adhering to coarse primary spherical Nb（C,N）.

关键词： Heat resistant steel Phase transformation Microstructure MX(X:C N) precipitate

Mechanical Properties and Temper Resistance of Deformation Induced Ferrite in a Low Carbon Steel

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Journal of materials science & Technology 2010年第12期26卷 1107-1113页

作者： Luhan Hao,Namin Xiao,Chengwu Zheng and Dianzhong Li shenyang national laboratory for materials science,Institute of Metal Research,Chinese Academy of sciences,shenyang 110016,china [a] shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of sciences shenyang 110016 china

The microstructures and mechanical properties of deformation induced ferrite （DIF） in the low carbon steel Q235 under different deformation temperatures have been investigated systematically. Through deformation induced ferrite transformation （DIFT）, ferrite grain can be refined to 3 μm and accounts for above 85% of the overall fraction. Yield strength of DIF （〉500 MPa） is increased by up to 100% compared with the conventional low carbon steel. Comparison of microstructure and mechanical properties in the Q235 steel with DIF and tempered DIF microstructure illustrates that the strengthening mechanism of DIF microstructure is the combination of grain boundary strengthening and carbon supersaturated strengthening. Electron back-scattered diffraction （EBSD） analysis and high magnification scanning electron microscopy （SEM） observation denote that high-angle grain boundary among ultrafine ferrite grain and the transformation product of retain austenite membrane along ferrite boundaries are responsible for the stability of ferrite grain size during tempering process. Transmission electron microscopy （TEM） analysis demonstrates that the transformation product of retained austenite membrane between ferrite grain boundaries is cementite.

关键词： Low carbon steel Deformation Mechanical properties Temper induced ferrite transformation Grain size resistance

Low Shear Strength and Shear-Induced Failure in Ti3SiC2

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Journal of materials science & Technology 2003年第3期19卷 197-200页

作者： Yiwang BAO Yanchun ZHOUHigh Performance Ceramic Division, shenyang national laboratory for materials science, Institute of Metal Research, Chinese Academy of sciences, shenyang 110016, china Lab. for Mat. Sci. Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

Shear strength and shear-induced Hertzian contact damage in Ti_3SiC_2 were investigated using double-notched-beam specimen and steel spherical indenter, respectively. The shear strength of 40 MPa that was only about 10% of bending strength was obtained for this novel ceramic. The SEM fractograph of specimens failed in shear test indicated a combination of intergranular and transgranular fracture. Under a contact load, plastic indent without cone crack could be formed on the surface of Ti3SiC2 sample. Optical observation on side view showed half-circle cracks around the damage zone below the indent, and the crack shape was consistent with the contrail of the principal shearing stress. The low shear strength and the shearing-activated intergranular sliding were confirmed being the key factors for failure in Ti3SiC2.

关键词： Ti_3SiC_2 Shear strength Contact damage Double-notched specimen