Papers by Keyword: FeSi

Abstract: The structure, phase composition, and morphology of FeSi and FeSi₂ nanofilms grown by three alternations of Fe (with a wedge-shaped thickness in the range 0 ‒ 2 ml) and Si (with a thickness 1 ML) depositions on a Si (001) 2×1 substrate heated to 400 °C were studied. According to Auger electron spectroscopy and electron energy loss, FeSi and FeSi₂ films were formed before and after the third deposition of Si, respectively. With this, a FeSi₂ film had ~1.5 ML of Si, which segregated on its surface. Both films consisted of a wetting coating (WL) and bulk phase forming at 2‒3 ML and after 3 ML of Fe, respectively. According to data of low electron energy diffraction, these films had a nanocrystalline structure. Moreover, according atomic force microscopy, deep square pores were formed in FeSi₂ films. They had a depth of 18‒10 nm, which was decreased and then increased before and, respectively, after Fe thickness ~ 3 ML.

Abstract: 800x600 Intermetallics are compounds of two metals or of metal(s) and semimetal(s). Their structures are usually different from those of the constituents. Some intermetallics are interesting functional materials, others have attracted attention as high-temperature structural materials. We remind the reader of some fundamentals of solid-state diffusion and to the major techniques for tracer diffusion measurements, interdiffusion studies and the growth kinetics of layers in solid diffusion couples. Starting from self-diffusion, which is the most basic diffusion phenomenon in any solid, the paper covers the main features of diffusion in binary intermetallics from the systems Cu-Zn, Ni-Al, Fe-Al, Mg-Al, Ni-Ge, Ni-Ga, Fe-Si, Ti-Al, Ni-Mn, Mo-Si, Co-Nb and Ni-Nb.. We illustrate the influence of phase transitions on diffusion and point out some common features of diffusion in intermetallics. We discuss in detail diffusion in silicides of iron, molybdenum and of silicides of refractory metals. We also consider aluminides of iron, nickel, and titanium and in the aluminium-magnesium system. We consider diffusion in intermetallics of the cobalt-niobium and nickel-niobium system and in in the Nb-Sn and V-Ga systems. We finish with some remarks about grain boundary diffusion in intermetallics. Normal 0 21 false false false UK X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";}

Abstract: An important process parameter in FeSi sintered alloys is the sintering temperature. If the sintering temperature can be reduced, the sintering process could be performed in less expensive furnaces. A densification model is here applied to experimental data. The model considers both grain size and density. After the model is applied to experimental data, the acquired model parameters allow the simulation of densification for other situations of temperature and heating rates. The model can be helpful to find suitable sintering temperatures in these alloys.

Abstract: The rate of reduction of chromium oxides in a stainless steel slag was studied in stagnant slag / metal melts at 1600 °C. The experimental results show that the magnesium contained in a FeMgSi ferroalloy has a reduction potential comparable to that of the silicon in a FeSi ferroalloy. On the other hand, it was confirmed that the rate limiting step in the reduction of the chromium oxides is the transport of chromium from the bulk of the slag to the slag / metal interface. The mass transfer coefficients for the reduction of chromium were estimated and are in good agreement with previously reported values.

Abstract: Elemental powder mixtures of Fe and Si were mechanically alloyed with a ball-mill. Mössbauer spectroscopy and X-ray diffraction were used to characterise the microstructural changes of these mixtures which are induced by high-energy ball-milling. Mössbauer spectra are discussed in terms of two main spectral components (corresponding to FeSi alloy and α-Fe) and the time dependence of the alloy formation follows a Johnson-Mehl type law. Calorimetry measurements show that the formed alloy is stable up to 800°C as no crystallisation or phase transformation peaks are observed. From X-ray diffraction, a crystallite size of 9 nm is obtained. Magnetic measurements at low temperature were carried out on the final alloy and the saturation magnetic moment at 4.2K is 0.44 μB/Fe.

Abstract: In the present study, the production of magnesium metal from Turkish calcined dolomite containing 43.20 % MgO and 47.46 % CaO via Pidgeon process was studied under the pressure of 1 mbar. In the experiments, Turkish ferrosilicon containing 75 % Si and 24 % Fe was used as reducing agent. Effects of FeSi addition (90-150 % of stoichiometric requirement of silicon) and time (60-240 min.) were investigated on recovering of metallic magnesium from calcined dolomite (dolime) at the temperature of 1200 °C. Effects of fluxing additive (CaF2), calcined magnesite and different temperatures on Mg recoveries and concentrations were also studied using with 100 % of stoichiometric requirement of silicon for 180 min. It was found that magnesium recovery increases with increasing FeSi addition, temperature, time, CaF2 addition and decreases with increasing calcined magnesite additions under the pressure of 1 mbar.