INTERFACIAL ADHESION OF COMPOSITIONAL GRADIENT TERNARY FCC ALLOY FILMS

摘要

Combinatorial materials design of thin films allows for the investigation of fundamental mechanic relationships and optimization of thin films for engineering applications. By depositing a wide range of compositions on a single sample, a systematic study of the full alloy composition of particular material system can be investigated for a number of different properties in a relatively short amount of time. Using an integrated shutter controller, specifically designed and manufactured to allow for precise control over coating design, ternary alloys with the full compositional range can be deposited on a single wafer. By specifically programming the shutters it was possible to create multilayered thickness gradients of three elements, which were then annealed to create thin films with a large compositional gradient across the wafer. The adhesion strength of an Al_2O_3 ALD coating on two such compositional gradient FCC alloy adhesion layers, AlCuAu and AuAgPd, was investigated as a function of the changing composition. The AlCuAu alloy sample consists of multiple phases and intermetallics across the wafer which are dependent on composition; whereas the AuAgPd alloy is a solid-solution across the compositional gradient. For this investigation, instrumented indentation with a conical diamond tip was used to locally measure the adhesion of the ALD coating with different adhesion layer compositions. By performing small arrays of indents over the surface of the coating, it was possible to test the adhesion-promoting properties of a broad spectrum of interface compositions in a single sample.