Multiphase Fe/N nanoparticles were synthesized by means of chemical vapor reaction, the influence of the preparing parameters on the properties of particles was studied carefully dur-ing the first nitriding process. T...Multiphase Fe/N nanoparticles were synthesized by means of chemical vapor reaction, the influence of the preparing parameters on the properties of particles was studied carefully dur-ing the first nitriding process. The optimum process was determined. Single phaseγ’-Fe4N was prepared by twice-nitriding. Multiphase iron-nitride really transformsγ’-Fe4N nanoparticle of sin-gle-phase and uniform. Moreover, the mechanism of nanoparticle nucleation and growth, including phase-transformation, was revealed. In addition, the mircograph, particle size, physical phases, schemical constituents and magnetic properties before and after phase-transformation were char-acterized initially.展开更多
The coarsened grain boundaries （GBs） with vein-like morphology frequently appear in the nitrogen diffusion layer of nitrocarburized carbon steels. The electron probe X-ray microanalysis shows that such vein-like GBs...The coarsened grain boundaries （GBs） with vein-like morphology frequently appear in the nitrogen diffusion layer of nitrocarburized carbon steels. The electron probe X-ray microanalysis shows that such vein-like GBs are rich in nitrogen and carbon atoms. Transmission electron microscopy and scanning electron microscopy further reveal that the coarsened GBs consist of γ＇-nitrocarbide （Fe4（C,N）） and ε-nitrocarbide lamellas that are formed during nitrocarburizing due to high nitrogen concentration at GBs. It is shown that many of {111}〈112〉 micro twins exist in the γ＇-phase lamellas and thin ε-phase slices prefer to nucleate at their twin boundaries with the orientation relationship of {0001}ε//{111}γ＇. Upon growing large γ＇-Iamellas may become faceted and thin ε-Iamellas may grow thicker and become the main portions in the vein-like GBs. The microstructure evolution occurring in the vein-like GBs can be depicted as： α ＋ [N]/[C] → ＋ [C,N] →ε-nitrocarbides.展开更多
基金supported by the China Funds of Excellent Youth and China Funds of Post Doctorthe National Natural Science Foundation of China and Post Doctor Funds of Heilongjiang Province.
文摘Multiphase Fe/N nanoparticles were synthesized by means of chemical vapor reaction, the influence of the preparing parameters on the properties of particles was studied carefully dur-ing the first nitriding process. The optimum process was determined. Single phaseγ’-Fe4N was prepared by twice-nitriding. Multiphase iron-nitride really transformsγ’-Fe4N nanoparticle of sin-gle-phase and uniform. Moreover, the mechanism of nanoparticle nucleation and growth, including phase-transformation, was revealed. In addition, the mircograph, particle size, physical phases, schemical constituents and magnetic properties before and after phase-transformation were char-acterized initially.
基金supported by the National Basic Research Program of China(No.2009CB623704)the National Natural Science Foundation of China(Nos.51071064 and 51171063)+2 种基金the Nature Science Foundation of Hunan Province(Grant No. 09JJ6002)Instrumental Innovation Foundation of Hunan Province(No.2011TT1003)the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province
文摘The coarsened grain boundaries （GBs） with vein-like morphology frequently appear in the nitrogen diffusion layer of nitrocarburized carbon steels. The electron probe X-ray microanalysis shows that such vein-like GBs are rich in nitrogen and carbon atoms. Transmission electron microscopy and scanning electron microscopy further reveal that the coarsened GBs consist of γ＇-nitrocarbide （Fe4（C,N）） and ε-nitrocarbide lamellas that are formed during nitrocarburizing due to high nitrogen concentration at GBs. It is shown that many of {111}〈112〉 micro twins exist in the γ＇-phase lamellas and thin ε-phase slices prefer to nucleate at their twin boundaries with the orientation relationship of {0001}ε//{111}γ＇. Upon growing large γ＇-Iamellas may become faceted and thin ε-Iamellas may grow thicker and become the main portions in the vein-like GBs. The microstructure evolution occurring in the vein-like GBs can be depicted as： α ＋ [N]/[C] → ＋ [C,N] →ε-nitrocarbides.
