温度梯度对定向凝固Al-4.5%Cu合金一次枝晶间距的影响

使用5kg坩埚下拉式定向凝固设备,对Al-4.5%Cu合金进行定向凝固试验,研究Al-4.5%Cu合金在不同温度梯度下一次枝晶间距的变化规律。结果表明:在其他凝固参数不变时,随着温度梯度的增大,一次枝晶逐渐变小,细密,挺直,基本呈平行状分布,同时计算的一次枝晶间距值与Hunt模型计算值接近,实验测得的一次枝晶间距的回归曲线为:y=2843478.3x2-70217.4x+543.8。用温度梯度较高的实验值来模拟时,可得到1λ=26.7G-0.5-135.9,一次枝晶间距λ1与G-0.5基本呈线性关系,这和Hunt模型分析结果一致。

Effect of Temperature Gradient on Primary Dendrite Spacing During Directional Solidification of Al-4.5%Cu Alloy

The drop-down 5kg crucible directional solidification equipment was used and the directional solidification experiment of Al-4.5%Cu alloy was carried out.The primary dendrite spacing of Al-4.5%Cu alloy under the conditions of different temperature gradient was studied.The results show that with the increasing of the temperature gradient,the primary dendrite spacing becomes smaller,meticulous and upright in other solidification parameters remaining unchanged.The basic shape is parallel to the distribution,meanwhile,the computed value of the primary dendrite arm spacing is closed to value with the Hunt calculated.The test measures the value of primary dendrite arm spacing in a regressive curve:y=2843478.3x2-70217.4x+543.8.With a higher temperature gradient to simulate the experimental values,the availability of λ1=26.7G-0.5-135.9 is got.The primary dendrite arm spacing λ1almost is linear with G-0.5.This is consistent with Hunt analyzed result.