The formation of interstitial solid solutions based on solvents showing the FCC structure: Elastic versus chemical interaction

Unit cell parameters anti densities were measured for the terminal solid so lutions of the late transition metals showing the fee structure (alpha -Co. Rh, Ir, Ni, Pd, Pt) with boron and partly with carbon. Especially the soli d solutions Pd(B) and Pd(C) were investigated because of the large homogene ity range up to the atomic fractions x(B)(f) = 0.186 and x(c)(f)similar or equal to0.05, respectively. The unit cell parameter increases and the: dens ity decreases with increasing boron and carbon content. Comparison of the c alculated and measured number of atoms in the Pd(B) and Pd(C) unit cells co nfirms the interstitial nature of both solid solutions. The difference betw een the measured dependence of the Pd-B shortest interatomic distances on t he solute content and those calculated according to the hard sphere model i ndicates a distinct negative deviation from additivity of the pure Form vol umes. The chemical (electronic) interaction plays a more important role tha n the elastic interaction (characterized by a size factor) in the formation of solid solutions of metals with the interstitially dissolved metalloids H, B, C, N and O. (C) 2001 Acta Materialia Inc. Published Elsevier Science Ltd. All rights reserved.