Effect of cooling rate in case of crystallization on phase composition and structure of wearproof hypereutectic aluminum-silicon alloy Alrezist
Statement of a problem. The research of logic of formation of structural and phase composition of the alloyed alloys on the basis of Al crystallized with cooling in range 103…105 °/sec, allows to change properties of these alloys in quite wide limits. Results of researches of the binary alloys of aluminum obtained at crystallization in the specified range of cooling are treated by a number of authors on the basis of formation of metastable phase diagrams. These diagrams can be obtained by extrapolation of phase equilibrium lines to regions of the overcooled state. Research objective. To analyzed results of researches of metallographic data and data of X-ray analyses from patterns with different velocity of cooling at crystallization. Description of obtained results. In article are investigated experimental silumin containing 35 % Si and alloying elements Fe, Ti, Zr. The phase-structural composition of high-siliceous hypereutectic silumin was considered in according with formation of metastable phase diagram on the basis of Al - Si - Fe system. The analysis of scientific publications showed, that at velocity of cooling in range 103…105 0/sec, double alloys with the eutectic or peritektic equilibrium and intermediate phases can be crystallized with forming in structure of the supersaturated solid solution on the base of aluminum in according with metastable diagram. Results of the microstructural and phase analysis of the granulated and cast alloy are analyzed on the basis of the triple phase diagram Al - Si - Fe. It is shown that in case of crystallization of granules, were suppressed such intermediated phases as FeSi2Al4 and FeSiAl5 with forming supersaturated a-Al solid solution. Conclusions. Data of an experiment confirm a possibility of extrapolation of a surface a liquidus to area of overcooling in case of suppression of crystallization of the intermediate phases according to the diagram Al - Si - Fe. In article the charting of formation of the metastable diagram on the basis of the stable Al - Si - Fe diagram with formation of abnormally supersaturated solid solution of aluminum and multiphase eutectic is considered.