Abstract
B4C/Al metal matrix composites (MMC) is one of the most potential neutron-shielding materials. Liquid stirring casting technology, at an elevated temperature, is the latest and most efficient method applied to manufacturing of such MMC. However the poor wettability of B4C/Al interface damages the mechanical properties ™, adding Al-Ti alloy into liquid Al to enhance the wetting is widely used in industry LJ.First-principles calculations based on density functional theory (DFT) can accurately provide the detailed atomic, electronic structures of the interface and quantitatively predict the work of adhesion [3]. To understand the alloying (or doping) effects in improving the wettability of B4C/Al interfaces, we investigated the Al(111)/AlB2(0001) and Al(111)/TiB2(0001) interfacial structures via a combined approach of experiment and DFT calculations. We find a larger work of adhesion (Wad) on the Al(111)/TiB2(0001) than the Al(111)/ AlB2(0001) interfaces. The subsequently calculated partial density of states (PDOS) of doped-diborides show fewer anti-bonding states in Al(111)/ TiB2(0001) than in Al(111)/AlB2(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 predicted improved wettability of Al/B4C by V-doping, because of the fewer anti-bonding states in vanadium-boron molecular orbitals. This first-principles CALPHAD result verifying with systematic experiments achieved a design of controllable complex interface of B4C/Al composite. This result integrated with magnetic-mechanical stirring have successfully guided the manufactured of 31%wt.B4C/Al composites with the B4C particles distributed relatively homogeneously in matrix. These MMC products are being applied to spent fuel storage projects of China nuclear power plants. 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.