Abstract
The present author previously worked out an elementary theory which could explain qualitaively the relation between the Young’s modulus and the degree of order regarding β-brass. By an analogous reasoning we examined in this paper the relation between the Young’s modulus and the composition of solid solutions. Denoting the force constant in regard to the interaction energy between A atoms, that between B atoms, and that between atoms A and B, by ξAA, ξBB and ξAB, respectively, we obtained the following results: (1) in case that the force constant ξAB is equal to the mean value of two force constants ξAA and ξBB, a linear relation between the Young’s modulus and the composition is obtained; (2) in case that ξAB is not equal to the mean value, a non-linear relation is obtained; (3) the theoretical curves obtained with appropriate values of ratio of the force constants agree well with the experimental ones; (4) using the value of ξAA obtained from the measured values of the lattice constant and the compressibility, we are able to estimate the magnitude of the Young’s modulus of molybdenum of polycrystalline form which agrees within about 10 per cent with the measured value.
