Burlachenko O. Development of technology for producing powders with quasi- or nanocrystalline phases by the method of mechanical alloying

A thesis for and candidate of technical sciences (PhD) degree, specialty 05.16.06. - Powder metallurgy and composite materials. National Technical University of Ukraine "Kyiv Polytechnic" Kyiv, 2015. Thesis is devoted to the development of technology for producing powders with quasi - or nanocomposite structures by the method of mechanical alloying (MA). The effect of parameters (speed, time and treatment environment) of the process of mechanical alloying in attritor and planetary ball mill of powder mixtures Al+Cu+Fe, (A1+Cu+Fe)+(Ti+Cr+Si) on the processes of formation of powders with quasicrystalline or approximant structure by mechanochemical synthesis (MCS) and powder FeCr-TiCN with nanocomposite structure by MA method are considered. The features of structural, phase transformations and changes in microhardness values, depending on the mode of mechanical alloying, were studied. The optimum modes of adding the surface-active substances (SAS) in the process of mechanical alloying the powder mixtures Al+Cu+Fe in planetary ball mill, that intensifies the process of quasicrystalline phase formation due to maintaining the optimum thickness of SAS layer on the particle surface during the whole process, were experimentally defined. It is shown that to increase the number of quasicrystalline ? - and approximant ? - phases in the products of mechanical alloying of powder mixtures Al+Cu+Fe, (A1+Cu+Fe)+(Ti+Cr+Si), it is necessary to carry out their heat treatment. Optimum conditions of heat treatment, when the content of quasicrystalline ? - phase reaches 95 wt.% and approximant - 68 wt.%, were defined. The assessment of efficiency of application of powders, produced by MA method, for plasma spraying of coatings with quasicrystalline, approximant and nanocomposite structures was made. Produced coatings are similar as to their characteristics to coatings from powders, produced by the melt spraying method. According to the obtained results the technological schemes of producing the powders - products of MA, the technical specifications for producing powders by MA method with quasicrystalline (TS 001-73-2009) and approximant (TS 002-73-2009) phases and the scheme of conglomeration of MA powder products for thermal spraying were worked out.