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FATIgUE CRACK gROWTH feATURE OF fe-Cr-Ni MATRIx COMPOSITE REINFORCED BY TITANIUM CARBIDE PARTICULATE AT 1023K

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Acta Metallurgica Sinica(English Letters) 1999年第6期12卷 0-0,0-0+0-0页

作者： Z. F. Wan x.D. Hui g.Q. Yuan Y. S. Yang x.C Chen Shandong University of Technology Jinan 250061 China Institute of Metal Research The Chinese Academy of Sciences Shenyang 110015 China Institute of Physics The Chinese Academy of Sciences Beijing 100080 China

The initiation and propagation of the short fatigue crack in a 10vol% titanium carbide particulate reichreed cast fe-26Cr-14Ni mathe coopsite at 1023K were *** is shown that the titanium carbide particulate may hinder the crack propagation and fatigue fracture of the composite. The relationships between fatigue crack propagation rate and stress intensity factor are da/dN=4.2×10-c(△K)4 for the matrix alloy and da/dN=1.4×10-19(△K)c for the composite. The fatigue thresholds of the composite and mathe alloy are 78 and 3.2MPa.m1/2, respectively. Microcracks initiate at the intedece between titanium carbide particulate and austenite and then propagate in carkide particles. The fracture sudece of the composite shows a distinct transition from wavy and serated cleavage near the threshold regime to striation-type splitting in the stable fatigue crack propagation stage and to a veined morphology characteristic in unstable rapid region.

关键词： fatigue crack initiation and propagation fe-Cr-Ni matrix composite titanium carbide particulate

Stabilizing nanograined fe-Cr alloy by Si-assisted grain boundary segregation

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Journal of Materials Science & Technology 2023年第3期134卷 223-233页

作者： x.F.xu x.Y.Li B.Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Intentional solute segregation at grain boundary(gB)can effectively stabilize the nanograined alloys by reducing the excess energy and mobility of gB,but it usually works for binary alloys with sufficient gB segregation ***,we found that the segregation of Cr can be enhanced in a nanostruc-tured fe-8Cr alloy with insufficient gB segregation tendency through the interaction of another solute Si(1.0 wt.%).After surface mechanical grinding treatment and subsequent annealing,the nanograined fe-8Cr-1Si is more thermally stable than the nanograined fe-8Cr,which is mainly attributed to the Si-enhanced Cr segregation as observed by Super-x energy-dispersive x-ray spectroscopy(EDS)mapping *** the grain refinement to nanoscale,the thermal stability is further improved due to the in-crease of Cr content at gBs and the precipitates formed at appropriate high *** present finding provides guidance for the development of advanced nanostructured ternary alloys.

关键词： Segregation grain boundary fe-Cr-Si alloy Nanocrystalline Thermal stability

Thermal stability of nanograins with grain boundary relaxation in microalloyed Cu-Sb and Cu-fe

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Journal of Materials Science & Technology 2023年第24期155卷 66-71页

作者： R.J. Zhu x.Zhou x.Y. Li Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China School of Materials Science and Engineering University of Science and Technology of China Shenyang 110016 China

grain refinement into nanoscale significantly enhances the strength and hardness of metallic materials but generally reduces the thermal stability by the introduced strong tendency for grain boundary(gB)*** nanograins through gB relaxation had been proven as an effective way in several metals recently when the grain size is below a critical ***,we discovered that the abnormally enhanced thermal stability induced by gB relaxation can be realized in 0.5%Sb or fe doped Cu,similar to that in pure *** observed critical grain sizes for gB relaxation in the two Cu alloys are almost the same as pure ***,the gB relaxation effect on thermal stability is kind of suppressed compared to pure Cu with similar grain sizes because of the segregation/precipitation of Sb/fe during the annealing process,which accelerates the detwinning and the failure of relaxed gBs.

关键词： Thermal stability grain boundary relaxation Nanograined Cu alloy Segregation Precipitate

STUDY ON CO-ELECTRODEPOSITION OF Bi-fe ALLOY FILMS IN ORgANIC BATH

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Acta Metallurgica Sinica(English Letters) 2003年第6期16卷 507-512页

作者： g.R. Li, Y.x. Tong and g.K. LiuSchool of Chemistry and Chemical Engineering, Zhongshan University, guangzhou 510275, China Sch. of Chem. and Chem. Eng. Zhongshan Univ. Guangzhou 510275 China

The cyclic voltametry and potentiostatic electrolysis was used to investigate the preparation of Bi-fe alloy films in LiClO4-DMSO (dimethylsulfoxide) system. The effects of several factors including the potential of deposition, current density and concentration of iron and bismuth in the solution on the fe content in the alloy deposits were studied. Experimental results indicated that the amorphous alloy films of Bi-fe containing fe 4.40wt%-33.67wt% could be prepared by controlling the system composition and deposition conditions. They were gray, uniform, metallic luster and adhered firmly to the copper substrates analyzed by EDS, SEM and xRD. After heat treatment of crystallization at 270℃ for 1h, the crystal phase of Bi-fe can be found in xRD patterns.

关键词： bismuth Bi-fe alloy film electrodeposition DMSO (dimethyl-sulfoxide)

Excellent strength-ductility combination in Co_(36)Cr_(15)fe_(18)Ni_(18)Al_(8)Ti_(4)Mo_(1)multi-principal element alloys by dual-morphology B2 precipitates strengthening

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Journal of Materials Science & Technology 2023年第3期134卷 60-66页

作者： x.S.Liu R.Li x.F.Fan Q.Q.Liu x.Tong A.x.Li S.xu H.Yang S.B.Yu M.H.Jiang C.Huo P.F.Yu M.T.Dove g.Li State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China College of Computer Science Sichuan UniversityChengdu 610065China School of Physical and Chemical Sciences Queen Mary University of LondonMile End RoadLondon E14NSUnited Kingdom School of Mechanical Engineering Dongguan University of TechnologyDongguan 523808China

Precipitation strengthening provides one of the most widely-used mechanisms for strengthen-ing multi-principal-element alloys(MPEAs).Here,we report dual-morphology B2 precipitates in Co_(36)Cr_(15)fe_(18)Ni_(18)Al_(8)Ti_(4)Mo_(1)MPEA obtained by thermo-mechanical *** microscopy charac-terization reveals that the dual-morphology B2 precipitates are either recrystallized B2 particles formed at the grain boundaries or triple junctions with recrystallization process,or rod-like within the non-recrystallized FCC *** dual-morphology B2 precipitates enhance the yield strength and ultimate tensile strength up to 1120 MPa and 1480 MPa,*** work suggests the mechanical proper-ties of the alloy can be optimized by B2 precipitation strengthening to meet the needs of engineering applications.

关键词： Multi-principal element alloys B2 precipitates Heterogeneous nucleation Precipitation strengthening

HREM STUDY OF THE AUSTENITE/MARTENSITE INTERFACES IN AN fe-9Ni ALLOY

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Acta Metallurgica Sinica(English Letters) 1997年第5期10卷 386-391页

作者： Li, g.L. Meng, x.M. Zhang, F.T. Wu, Y.K. Inst of Metal Research Chinese Acad of Sciences Shenyang China

The atomic level structures of fcc/bcc interfaces in an fe-9Ni alloy have been examined by means of HREM. It has been found that the orientation of γ prime /α interface had great effects on its atomic structure. These interfaces with different orientations may be composed of only structural ledges, structural ledges with misfit dislocations, superledges with misfit dislocations or only misfit dislocations. A structural model of growth ledge was suggested. The terrace of growth ledge was composed of structural ledges or misfit dislocations. The atomic structure of the riser of growth ledge was the same as that of the side facet of γ prime lath, which is composed of superledges with misfit dislocations.

关键词： Austenite Electron microscopy Interfaces (materials) Martensite Nickel alloys

MICROSTRUCTURES AND OxIDATION RESISTANCE OF fe_3Al WELD OVERLAY

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Acta Metallurgica Sinica(English Letters) 2001年第4期14卷 253-256页

作者： x.g. Mi x.Q. Yu, Y.S. Sun and J.R. Sun Department of Materials Science and Engineering, Southeast University, Nanjing 210096, China Dept. of Mat. Sci. Southeast Univ. Nanjing 210096 China

Using the fe3Al electrode through manual arc surfacing (MAS), fe3Al coatings were deposited on the stainless steel substrate. The microstructures, hardness and oxidation resistance of the weld overlay were investigated. The results show that crack-free overlays can be obtained when pre-heating the substrate at 500°C and postweld heat treatment at 700°C are used. Elements of Al, Cr and Ni, etc. transfer between the substrate and the overlay, but this does not influence the microhardness of the substrate and the fe3Al overlay. Oxidation tests show that the fe3Al overlay has excellent oxidation resistance in comparison with the stainless steel substrate at 800°C and 900°C.

关键词： Aluminum Intermetallics Iron Microstructure Oxidation resistance

EFfeCTS OF HDDR PROCESS ON STRUCTURE AND MAgNETIC PROPERTIES OF Nd(fe,Ti)_(12)N_δ PREPARED BY MECHANICAL ALLOYINg

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Acta Metallurgica Sinica(English Letters) 1998年第1期11卷 68-78页

作者： B.ZCui x.K.Sun x.g.Zhao W.Liu Q.F.xiao T.Zhao Z.D.Zhang Y.C.Sui Chinese Acad of Sciences Shenyang China

The effects of the hydrogenation-disproportionation-desorption-recombination (HDDR) process on the structure and the magnetic properties of the mechanical alloying (MA) prepared Nd8fe84 Ti8 alloy and its nitride counterpart have been studied in detail. It has been found that Nd(fe, Ti)12Hδ is formed in the temperature range from 300 to 550°℃. The disproportionation is ready to start at 550°℃ and is complete at 960°℃.The desorption and the recombination are almost synchronized. The phase of Nd(fe,Ti)7 is formed at 750°℃ during the HDDR treatment. With increasing temperature of HDDR process, the metastable structure of TbCu7 type is gradually transformed into the structure of ThMn12 type. The intrinsic coercivity and the maximum magnetic energy product increase with increasing temperature of HDDR process.

关键词： Nd(fe Ti)_(12)N_δ compound,magnetic property hydrogenation

Structure evolution of the fe_(3)C/fe interface mediated by cementite decomposition in cold-deformed pearlitic steel wires

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Journal of Materials Science & Technology 2022年第6期101卷 28-36页

作者： Y.T.Zhou x.H.Shao S.J.Zheng x.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology School of Materials Science and EngineeringHebei University of TechnologyTianjin 300130China

Cold-drawn pearlitic steel wire is irreplaceably used in industry owing to its outstanding mechanical property which is dominated by the cementite/ferrite(fe_(3)C/fe) interfaces in the material. However, the fine structures of the fe3C/fe interfaces in the deformed wires are less known to date. In this work, transmission electron microscopic investigation was performed on the atomic structures of the interfaces with the Isaichev orientation relationship(OR) in the wires with progressive deformation strains. In addition to the effect of the dislocation/interface interactions, this work revealed that the deformation-induced partial decomposition of cementite plays an important role in the interface reconstruction during deformation. The interfacial carbon vacancies generated by cementite decomposition and particularly, the amorphization of cementite layers in the sample with ε > 1 could effectively annihilated the interfacial dislocations and consequently relaxed the interfacial stress. The correlations between the interface structure changes and the mechanical properties of the wires were discussed.

关键词： Pearlitic steel Cementite decomposition Interface structure Deformation Transmission electron microscopy