Nitride phase composition

Purpose of this work was to study the structure, phase composition and mechanical properties of surface diffusion layers formed in the preliminary cold deformed a-Fe and Fe-Ni alloys after nitriding. 

The preliminary plastic deformation considerably effects on the phase formation, structure, microhardness and thickness of nitrided layers in -Fe and Fe-Ni alloys. The high microhardness of the diffusion layers results from the formation of the s- and y- nitrides. Iron doping with Ni leads to changing of the s-, f-phases composition. The existence of narrow intervals of deformations of 3-8 % and 20-30 %, in which the considerable (about 2 times) rise of microhardness of surface nitrided layers due to accelerated formation of s- and f-phases, was found. 

Klemm H, Herrmann M, Schubert C (1996) The Influence of the Grain Boundary Phase Composition on the High Temperature Properties of Silicon Nitride Materials. In Parilak L, Danninger H, Dusza J, Weiss B (eds) Proc Int Conf Deformation and Fracture in Structural PM Materials, IMR SAS Kosice 2 75... 

W.M., Influence of deposition temperature, gas pressure, gas phase composition, and RF frequency on composition and mechanical stress of plasma silicon nitride layer. J. Electrochem. Soc. 132 893 (1985). 

The nitrogen pressure determines the composition of the nitride if equilibrinm is attained. Thermochemical models have been established that correctly predict pressure-temperature-composition (p-T-x) relationships for nitride phases. ... 

If the solid solution of nitrogen in Zr, o -Zr(N), which exists up to a composition Zr2N , is not considered as a nitride phase, the Zr N system is characterized by the presence of only one nitride phase, 5-ZrNi c up to a composition of approximately [N]/[Zr] = 1. It should be mentioned that none of the subnitride phases that exist in the neighboring systems Ti-N and Hf-N occur here. In Massalski s compilation ... 

While at least 15 different nitride phases with compositions ranging between W2N and WN2 have been reported, none of them appear to be very well characterized. As for the Mo-N system, an fee nitride WNi x appears to exist since nitridation experiments under pressure in the Mo-W-N system have shown that the fee MoNi x phase is able to form extended solid solutions with the isotypic phase WNi x. The pressure... 

Skibska, M., Szulc, A., Mukasyan, A. S., Shugaev, V. A., and Shiryaev, A. A., Microstructural peculiarities of silicon nitride formation under high nitrogen pressures. Part II The effect of nitrogen pressure on SHS SijN4 morphology and phase composition. Int. J. SHS, 2,247 (1993b). 

K, or boron nitride deposited on inductively hot graphite, or other materials By controlling the reaction parameters (gas-phase composition, T, etc.), microcrystals and even small single crystals of different B C stoichiometries can be deposited . 

By heating of NH4TCO4 in ammonia at 900-1100 "C an fee phase was detected with a lattice constant varying from 3.980 to 3.985 A depending on the nitrogen content. The maximum nitrogen content reached the composition TcNo.ye- Probably, the nitride phase corresponds to TcN having an NaCl structure [7,14]. 

Si MAS NMR is a very useful technique to study the crystal-phase composition and transition in silicon nitride and carbide [27,28]. The a phase of... 

This is the most widely used method for the determination of the phase composition of powders. The x-ray diffractometer contains a source of monochromatic x-rays that irradiate the sample and are diffracted from atomic planes and detected. The angle of diffraction of x-rays by the crystalline planes is characteristic of the crystal structure, and the intensity of scattered radiation is characteristic of the atomic composition. In recent years, automated data processing has enabled higher accuracy and speed. A number of problems are encountered in the quantitative determination of phases in fine powders. Some of these are overlap of phase peaks (e.g., in silicon nitride), orientation of grains, and presence of coarse particles. The last produces distortion of the diffraction data. A number of standard reference materials for XRPD have been developed for use in improving the quality of data [37]. 

Figure 6 pvra the mole fractions at equilibrium for the system 1 C, 4 H, 3 O, 2 Fe. This mixture (CH + FejOj) has been studied to provide data on the equilibrium vapour phase composition in a plasma furnace used for the reduction of iron oxide. A priori this diagram shows that the reduction of iron oxide to iron attains 1(K)% in the vapour phase. As we have shown previously for the nitrides the problem of condensation remains tmresolved, however, experimental results indicate that the cooling rate has little effect on the overall yield in that particular case. Figure 7 shows the reducing powers of hydrogen and carbon. 

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