THE SPECIFIC FEATURES OF PHASE TRANSFORMATIONSDURING MECHANOCHEMICAL ALLOYINGIN THE Fe–Ni–Cr–Cu–Si–B–C COMPOSITE
In the presented work, the process of mechanochemical alloying of a mixture of Fe, Ni, Cr, Cu, Si, B, C powders in an MPP-2-1K planetary mill with a duration of up to 15 min is carried out in order to study the possibility of obtaining a surfacing powder for flame surfacing. To establish the features of the chemical interaction during mechanochemical alloying between the components of the charge, the sequence and nature of the formation of the phase composition of granular compositions, an X-ray phase analysis of the powder material was carried out on a D8 ADVANCE “Bruker Elemental GmbH” diffractometer. The morphology of granules after MCL was carried out on a JEOLJXA-8230 scanning (raster) electron microscope (SEM). To determine the melting point of the obtained composition, thermogravimetric analysis was carried out on a synchronous thermal analyzer TG-DTA/DSC with a quadrupole mass spectrometer: STA 449 F3 Jupiter® “NETZSCH”. The results of the study showed that in the Fe–Ni–Cr–Cu–Si–B–C powder composition during mechanical activation, both stable and metastable phases are formed. It was revealed that already after 1 min of mechanochemical alloying, numerous new phases are formed, and by 15 min a multiphase system is formed, including intermetallic compounds (Fe0.95Ni0.05, Cr1.07Fe18.93, etc.), carbides (Fe3C, Cr15.58Fe7.42C6, etc.), borides (Ni75Si24B0.04, etc.) and silicides (Ni0.92Si0.08, Cr5Si3). The main reason for the phase formation during mechanochemical alloying is the impact of the impact of grinding bodies (balls), as a result of which plastic deformation of the particles of the initial components, their destruction and welding along the formed juvenile surfaces, accompanied by exothermic effects with the formation of intermediate liquid phases, is carried out. As a result, the contact surface of the reagents sharply increases and composite particles are formed. During the impact, complex and poorly studied processes of chemical interaction, diffusion of components, phase and structure formation occur.