负温度梯度熔体凝固过程中的形核与再辉行为

The Conduct of Nucleation and Recalescence in the Process of the Negative Temperature Gradient Melt Solidification

研究了63～292K热力学过冷度范围内,Cu-Ni单相合金的凝固组织演化规律,分析了负温度梯度熔体凝固过程中的形核与再辉行为。结果表明:①负温度梯度熔体凝固的冷却曲线上有较明显的形核特征;②在负温度梯度熔体凝固冷却曲线的快速再辉阶段,出现了明显的“二次再辉”特征,此“二次再辉”的本质有别于慢速凝固阶段的二次再辉,因此称之为“伪再辉”。

In this paper, the solidification microstructure evolution of the single-phase Cu-Ni alloy, which has thermodynamic supercooling degree of 63～292K, is investigated. Meanwhile, the conduct of nucleation and recalescenc is analyzed in the process of negative temperature gradient melt solidification. The research result shows that: The character of nucleation is obvious relatively along the cooling graph of the negative temperature gradient melt solidification; The character of 'second recalescence' appears obviously in the phase of fast recalescence of the cooling graph of the negative temperature gradient melt solidification. The 'second recalescence' is called 'pseudo-recalescence' because it is essentially different from the second recalescence present in the phase of slow solidification.