Al-0.53Zn合金近快速定向凝固条件下的胞晶间距选择

CELLULAR SPACING SELECTION OF Al-0.53Zn ALLOY UNDER NEAR-RAPID DIRECTIONAL SOLIDIFICATION CONDITION

利用Bridgman装置考察了Al—0．53Zn单相合金在近快速定向凝固条件下的胞晶间距选择规律．结果表明：在给定的温度梯度下，随着生长速度的增大，定向凝固组织均为胞状晶，胞晶间距λ的分布存在一个较宽范围，其最大、最小及平均间距随生长速度v变化的实验规律可表示为：λmax＝948．51v(-0.4961),λmin＝661.16v-0.5015,KGT理论模型较好地预言了近快速定向凝固条件下胞晶平均间距选择的实验规律.台阶变速实验表明，胞晶平均间里的选择具有显著的历史相关性.

In order to investigate the response of primary cellular/dendritic spacing selection to the variation of growth velocity under near-rapid directional solidification condition, anAl-0.53Zn alloy is directionally solidified with Bridgman apparatus. The results show that atthe given temperature gradient the microstructures is cells and there exists a wide distributionrange of cellular spacing. The maximum, A..., minimum, and average cellular spacing,A, as fullctions of growth rate, v, can be given by λmax=948.51v(-0.4961),λmin=661.16 v(-0.5015),λ=412.41 v(-0.5049), respectively. The experimental results are compared with that predicted bythe current KGT model, and a good agreement is found. Moreover, it is found that the averagecellular spacing is also remarkably history-dependent.