TiB_2粒子细化铝合金的电子理论分析

ELECTRONIC THEORETICAL ANALYSIS ON REFINING OF Al-Ti-B MASTER ALUMINUM ALLOY

利用固体分子经验电子理论对在铝合金细化过程中起主要作用的TiB2 粒子的价电子结构进行了分析和计算。结果表明 ,TiB2 中的共价电子主要集中在最强的B B键上 ,其晶体中的B B键可形成稳固的六边形结构。大量弥散分布的TiB2 粒子在铝熔体中形成了与石墨类似的连续网状结构 ,为TiAl3 在其上成核提供了平面衬底。TiB2与TiAl3 之间的润湿角较小 ,使成核所需的能量较低。加之TiAl3 与α Al之间具有良好的晶格对应关系 ,从而形成了大量的异质晶核 ,使铝合金得到细化。

The valence electron structure of TiB 2 playing an important role during the refining process of aluminum alloy was analyzed on the basis of the empirical electronic theory of solids and molecules. The results show that the common electrons mainly focused on the strongest bond B-B that can become the most stable hexagon structure. Lots of dispersed TiB 2 particles in aluminum melt can form reticulation structure similar to that of graphite and become a good plane underlay for forming nucleus of TiAl 3. Wetting angle between TiB 2 and TiAl 3 is small, which makes TiAl 3 need less energy in nucleus forming process. There is a good matching relationship between TiAl 3 and Al, a lot of heterogeneous crystal nuclei are created, which is beneficial for the refining of aluminum alloy.