from the conferences organized by TANGER Ltd. provisional website
In the present work, the route of preparation for specimens by high temperature aging of preliminary pressed mixture (briquettes) of the Fe powder with differ nitride powders (BN, Si3N4, AlN) is suggested and the microstructure and magnetic properties of the synthesized alloys are studied. The pressed briquettes from iron and nitride powders mixture in desired proportions were heated in the nitrogen atmosphere till temperatures of 1300-1550 °C and held for 3 hours, and subsequently cooled along with the furnace. As a result of the solid or liquid-phase reaction within the sintering process, the ceramic is formed upon the heat-treatment of briquettes and the spherical metal fragments exudation on the surface of ceramic part of the briquette was observed. After aging the sample (Fe+33 wt.% BN) the composition of the spherical metallic fragment was comprised of 50 % Fe–30 % N–20 % В. Themicrostructure includes the eutectic structure between primary iron grains. The eutectic consists of Fe precipitates, as dendrites and the dark boride phase. In eutectics, the boride phase composition changes B from 9 to 24 at. % close to the stoichiometry of the metastable Fe3B compound. The microstructure of the metallic fragment of the sample (Fe + 35 wt.% Si3N4) consists of grains of the Fe-Si phase with composition 17 at. % Si – 83 at. % Fe. The microstructure of the metallic fragment of the sample (Fe + 22.5 wt.% AlN) consists of grains of the Fe-Al-based phase with composition 70 at. % Fe – 14.5 at. % Al – 15.5 at.% N. The obtained metal fragments are characterized by relatively high coercivity (8-10.3 kA/m) comparable to those fine films and nanosized iron powders produced by gas nitrogenation.Keywords: Powder metallurgy, boron nitride, silicon nitride, aluminium nitride, microstructure
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