Influence of the cooling rate on the structure formation of the AM4.5kd (VAL10) alloy

High-strength cast aluminum alloy AM4.5Kd (VAL10) belongs to the Al-Cu system and due combination of a high level physical, mechanical operational properties, is widely used in high-tech industries technology: aviation, space, shipbuilding, transport. Products from are obtained by all known methods casting (in sand molds, chill mold, under pressure), differing cooling rates. This has significant effect on structure properties alloy, not only as-cast, but also heat-treated state, which determines relevance scientific work this direction. The article presents results study microstructure with change its rate during curing process (Vcool.) 0.4 °C/s ≥ 105 °C/s. was melted, refined and, at temperature 750°C, poured into molds different heat sinks. It shown that an increase hardening leads decrease size structural components, particular, (Alα) solid solution crystals their microhardness. At °C/s, corresponding solidification sandy form, primary Alα formed form coarsened dendrites average slightly larger than 800 μm, along boundaries fine network particles Al3Ti, Al12Mn2Cu phases Alα+СuАl2 eutectics formed. With rate, branching volume fraction finely differentiated eutectic increase, cooperative growth maintained throughout entire range rates studied. value dendritic parameter regularly decreases practically unchanged shape factor crystals, almost up Vcool. ≈ 1.45 3.15. A similar dependence macrograin found. Its anomalous recorded 120 commensurate cooled In work, such discrepancy explained standpoint theory nucleus crystals. Keywords: microstructure, (VAL10), formation, size.