Crystal-Structure Contribution to the Solid Solubility in Transition Metal Alloys

The solution energies of $4d$ metals in other $4d$ metals as well as the bcc-hcp structural energy differences in random $4d$ alloys are calculated by density functional theory. It is shown that the crystal structure of the host plays a crucial role in the solid solubility. A local virtual bond approximation accounts for the calculated solution energies and explains the substantial reduction in structural energy caused by randomness.