Revealing the adhesion strength, fracture mechanism and stability of semi-coherent Al(111)/MgAlB4(0002) interfaces: A first-principles investigation

In the present study, we systematically explored the kinetic and thermodynamic properties of the ceramic phase MgAlB₄ based on the first-principles calculations, and the adhesion work (W_ad), interfacial energy (γ), atomic structure, and interfacial fracture mechanism of semi-coherent Al(111)/MgAlB₄(0002) interfaces were also explored. The results show that the interfacial constructions of the MT (bridge) sites are unstable and the atoms at the interface move to the interior after relaxation. In addition, the obtained adhesion work and interfacial energy indicate that the stability of the HCP (hollow) sites interfacial configurations are higher than the MT and OT (on-top) sites. The interfacial structure of B-terminated Al(111)/MgAlB₄(0002) HCP site is the most stable because it has the largest adhesion work and the smallest interfacial energy. The interfacial electronic structures indicate the B-Al covalent bonds are formed at the Al(111)/ MgAlB₄(0002) interface, while mechanical failure in the B-terminated HCP site interfacial configuration occurs in the Al phase. Ultimately, the results show that the ceramic phase MgAlB₄ particle reinforcement can effectively enhance the strength and plasticity of the Al-based composites.