Abstract
In order to improve the accuracy of rapid evaluation of the modification effect of Al-Si alloy in front of the furnace, the relationship between resistivity change and modification level during melt solidification was experimentally studied. A melt resistivity monitoring system was designed for practical application, including a sample cup, sample cup base support, vacuum aspiration unit, constant current power supply, data acquisition module, and computer. The monitoring system was used to monitor the changes in temperature and resistivity parameters during solidification of ZL101A alloy melt treated with different amounts of Sr modifier. It was found that the curve of melt resistivity changes with temperature at the eutectic solidification stage had a plateau, and the resistivity plateau value decreased with the better alloy modification effect. Therefore, a rapid evaluation model was established of the hypoeutectic Al-Si alloy modification effect in front of the furnace based on resistivity change during melt solidification. The experimental results showed that the evaluation of the modification effect of the hypoeutectic Al-Si alloy could be completed within 3 minutes by using the monitoring system and evaluation model designed in this paper. The accuracy of the evaluation of modification level error within ± 0.5 reaches 80 % taking the metallographic observation method as the standard.

Key words
resistivity, monitoring device, hypoeutectic Al-Si alloys, modification effect, rapid evaluation

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