Interfacial Creep in Multi-Component Materials Systems

Naval Postgraduate School, Monterey CA

Investigators

Abstract

0075281 Dutta Although interfacial sliding has been noted in many materials systems, a clear mechanistic picture of the phenomenon is yet to emerge. Part of this is associated with the difficulty of designing experiments which allow the strain response of the interface to be distinguished from obfuscating superimposed effects (such as creep of one or both components adjoining the interface). In previous NSF work, it was demonstrated that this challenging task could be accomplished by a combination of carefully designed experimental and analytical approaches. The current research aims to: (1) develop experimental and analytical approaches to study interfacial creep in both bulk and thin film materials systems; (2) develop mechanistic insight into interfacial sliding by correlating the sliding kinetics with the interfacial morphology, structure and chemistry; (3) generate sliding kinetics data for selected interfaces of practical importance, and (4) evaluate the impact of sliding on the performance of two engineering systems of importance (fibrous composites and film-substrate systems). %%% Interfaces between dissimilar materials are critical to the performance of many engineering materials. Often, large shear stresses exist at the interface, and at least one of the materials adjoining the interface can be subjected to high homologous temperatures during service. This enables diffusionally accommodated interfacial sliding (interfacial creep) to occur, with potentially severe impact on the dimensional stability and reliability of the system of interest. Possible examples include metal-matrix composites subjected to thermal cycling, thin-film microelectronic devices subjected to Joule heating during service or thermal cycling during fabrication, and flip-chip solder joints in power electronic packages subjected to thermal excursions during on/off cycles. ***