Calculated Elastic Constants of Dilute Alloys

The elastic constants of dilute alloys are studied using a Green's function technique. An impurity model with central and non‐central force‐constant changes extending upto second neighbours of the impurity is employed to describe the impurity in a f.c.c. lattice and explicit expressions for changes in elastic constants have been obtained in terms of the t ‐matrix. The effect of volume changes on elastic constants is discussed. The contribution to the bulk modulus from the electron pressure is also included. Especially the changes in different elastic constants are calculated in a number of dilute alloys based on Cu, Ag, and Au. The calculated results are compared with available experimental measurements. The obtained force‐constant changes are found to be symmetry dependent.