过渡元素改善B_4C/Al材料界面润湿性的机理研究（英文）

Improving Al Wettability on B_4C by Transition Metal Doping: a Combined DFT and Experiment Study

B_4C/Al复合材料是目前最理想的中子吸收材料,但工业上常用的液态搅拌法制备过程中存在着界面润湿性差的问题。结合实验及第一性原理的方法,通过研究Al(111)/AlB_2(0001)和Al(111)/TiB_2(0001)界面的结构来分析工业上添加过渡元素Ti对B_4C/Al界面润湿性的改善机制。通过计算发现,Al(111)/TiB_2(0001)界面相对Al(111)/AlB_2(0001)界面具有更高的粘附功值,说明其界面结合更强。进一步对比Ti掺杂二硼化物和AlB_2的偏态密度结构,发现Ti掺杂体具有较低的反键态,表明Ti-3d和B-2p轨道电子杂化后,在B、Ti原子间形成了较强的化学键,从而促进了Al(111)/TiB_2(0001)界面处的强结合作用,提高了Al(111)/TiB_2(0001)界面粘附功,故而改善了B_4C/Al界面的润湿性。根据同样的理论依据,V掺杂体也具有较低的反键态,V和B之间的强结合效果或许能够改善B_4C/Al界面的润湿性,成为又一理想的溶体改性掺杂元素。

B_4C/Al MMC is one of the most potential neutron-shielding materials. The poor wettability of B_4C/Al interface damages the mechanical properties. To understand the alloying（or doping） effects in improving the wettability of B_4C/Al interfaces,we investigated the Al（111）/AlB_2（0001） and Al（111）/TiB_2（0001） interfacial structures via a combined approach of experiment and DFT calculations. We find a larger work of adhesion（Wad） on the Al（111）/TiB_2（0001） than the Al（111）/AlB_2（0001） interfaces. The subsequently calculated partial density of states（PDOS） of doped-diborides show fewer anti-bonding states in Al（111）/TiB_2（0001） than in Al（111）/AlB_2（0001）,which contribute to a stronger bonding between Ti-3d and B-2p states and lead to a higher Wad and better wetting. Furthermore,we predict improved wettability of Al/B4 C by V-doping,because of the fewer anti-bonding states in vanadium-boron molecular orbitals. The same approach developed in this study may be applied for general design of alloy elements to improve the interfacial wetting of alloy-semiconductor systems.