Coherency Strain Modeling Of Elastic Moduli In CU/NB Multilayers
An anomalous decrease in the elastic moduli of Cu/Nb multilayers has been observed via acoustic wave measurements. The decrease occurs for (111) fcc Cu and (110) bcc Nb layered structures with repeat periods between 1 and 5 nm. The coherency strain model has been used to simulate modulus enhancement in noble/transition metal multilayers. This approach addresses the atomic displacements corresponding with the lattice distortions of biaxially stressed layers. Elastic moduli are derived with respect to higher order differentials of a Born-Mayer type potential for nearest neighbor ions. The elastic moduli anomalies of Cu/Nb multilayers will be modelled within this conceptual framework.