MC碳化物非平衡凝固液/固界面结构及生长机制

LIQUID/SOLID INTERFACE STRUCTURE AND GROWTH MECHANISM OF MC CARBIDE UNDER NON-EQUILIBRIUM SOLIDIFICATION CONDITIONS

在冷却速度为102-105K/s的激光快速凝固条件下,对Jackson因子约为5-7的TiC型MC碳化物典型小面品体液/固界面结构、生长形态及生长机制进行了系统的实验研究和理论分析.结果表明,尽管MC碳化物的生长形态随着凝固冷却速度的变化而发生显著变化,但其液/固界面始终保持原子尺度上光滑。其微观生长机制始终为台阶侧向生长,在102-105K/s凝固冷却速度条件下, MC碳比物生长机制并未发生山侧向生长机制向连续生长机制的转化.

The liquid/solid interface structure and growth mechanisms of the faceted phase TiC type MC carbide were studied with solidification cooling rate ranging from 10(2) to 10(5) K/s. Results show that within the present solidification cooling rate ranges, although the growth morphologies of the MC carbide vary remarkable, the liquid/solid interfaces are always atomically smooth and the growth mechanisms are always lateral growth. The growth mechnism transition from lateral to continuous growth modes, which is hypothesized by the classical crystal growth theory, is not observed for the TiC carbide within the above solidification cooling rate range.