Influence of the structure of the AlSi20 foundry alloy on the microstructure and viscosity of the Al-6% Si model silumin in solid and liquid states

The influence of the structure of starting charge alloys Al-20 wt % Si on their structure after single remelting and crystallization with an identical cooling rate of 20 K/s is investigated. It is established that the structural transformation from the starting charge alloys stably retains, being translated in the “solid-liquid-solid” system. The viscosimetry investigation of the melts obtained from the coarse-crystalline and the fine-crystalline charge alloys in the heating mode to 1350°C and the subsequent cooling confirmed the conclusion that these melts are translators of structural information. It is established that the branching temperature (hysteresis) of viscosity polytherms (t _h) in the heating and cooling modes for the melt made from the coarse-crystalline charge alloy is 1100°C, while that for the fine-crystalline charge alloy is 1000°C. It is noted that, in the second case, the viscosity in the cooling mode below t _h is elevated, while the polythermal branch ascends more steeply. These results indicate the favorability of using special methods of processing the charge metals with the goal of laying positive structural information into them. The use of this approach is most reasonable when obtaining aluminum-based foundry alloys.