7075Al合金LSC铸锭二次加热中的液固相体积分数

Liquid Fraction of 7075 Aluminum Alloy Cast by LSC During Reheating

研究了液相线半连续铸造法制备的 70 75Al合金坯料在二次加热过程中液固相比的变化 ,分别用电阻法、热涵法测定出不同温度下 70 75Al合金的液相体积分数 ,并与图像法进行了比较·结果表明 ,在 60 0℃左右 ,电阻法与用热涵法、图像法所测的实验结果基本一致 ,正确反映了加热过程中合金的液固相变化规律·用电阻法能方便有效地测定二次加热过程中半固态 70 75Al合金的液固相比 ,具有实时性强的优点 ,在 60 0～ 62 0℃时 ,70 75Al合金液固相比为 3 0 %～ 5 0 % ,完全适于合金的半固态成形·

The solid fraction of 7075Al alloy cast by liquidus semi continuous casting (LSC) during reheating were studied by two methods, namely, resistance measurement and thermal analysis (DSC measurement). The results of resistance measurement are similar to the results of DSC measurement and are also consistent with optical image observation. The results also show that resistance measurement can efficiently and easily measure the solid fraction of semi solid 7075Al alloy during reheating in real time. With the temperature varying from 600?℃ to 620?℃, the solid fraction of the 7075Al alloy varies from 30% to 50%, which is very suitable for thixoforming.