Kaverinsky V. Effect of disperse modifiers on the structure and properties of aluminium and iron-carbon alloys.

The effect of modification using refractory compounds powders capable to dissolve in a liquid metal and become additional centres of forced bulk crystallization at the time of its beginning, which increases the dispersion of the metal structure was theoretically and experimentally confirmed. Mathematical models and computer programs for their realisation for describing of carbides, nitrides and intermetallic compounds behaviour in melts based on iron and aluminium were made. Using the models, as well as in laboratory experiments the features of the dispersed particles size distribution function evolution in the melts based on iron and aluminium were investigated. From the analysis of the results recommendations to improve the effect of disperse modifiers on the structure formation of aluminium alloys low alloyed steels and cast irons have been made. In laboratory modifying experiment average areas of cast macro-grain of aluminium was declined by 6 ... 8 times and by 4.8 ... 5.2 times in Al-Si alloy AK7. The average linear grain size in the microstructure decreased up to 21.4 %. An increase in hardness up to 20 - 23 % was achieved. In industrial experiment showed refinement of graphite inclusions and elimination of rough carbide eutectics. Increase of strength to 15 - 20 % and Brinell hardness to 25 - 35%, as well as extending the life of products (molds) by 1.4 - 2.0 times were achieved.