Effects of transition metals (Nb, Mo and Cd) and main group metals (In, Ge and Sb) on mechanical properties of Al2Cu: a first-principles study

It is well known that two significant ways to influence the properties of Al-Cu alloys are strengthening phases and doping. In order to investigate the effect of doped atomic types on the performance of reinforced phase θ (Al2Cu), first-principles calculations based on density-functional theory are used to investigate the elastic constants and electronic structures of the Al-Cu-X (X= Nb, Mo, Cd, Ge, In, and Sb) doped systems. The results show that, different types of doped atoms have different effects on the mechanical properties and bonding characteristics of Al2Cu. The transition metals (Nb, Mo, and Cd) cause Al2Cu to form metallic bonding. Due to the physical properties of the metallic bonding, the doped structures have better plasticity than the θ phase. On the contrary, the main group metals (In, Ge and Sb) cause Al2Cu to form strong covalent bonding. Due to the physical properties of the covalent bonding, the strength of the doped structures is better than the θ phase.