First-principles study on stability of transition metal solutes in aluminum by analyzing the underlying forces

Although there have been some investigations on behaviors of solutes in metals under strain, the underlying mechanism of how strain changes the stability of a solute is still unknown. To gain such knowledge, first-principles calculations are performed on substitution energy of transition metal solutes in fcc Al host under rhombohedral strain (RS). Our results show that under RS, substitution energy decreases linearly with the increase of outermost d radius r(d) of the solute due to Pauli repulsion. The screened Coulomb interaction increases or decreases the substitution energy of a solute on condition that its Pauling electronegativity scale phi(P) is less or greater than that of Al under RS. This paper verifies a linear relation of substitution energy change versus r(d) and phi(P) under RS, which might be instructive for composition design of long life alloys serving in high stress condition. (C) 2015 AIP Publishing LLC.