Strain relaxation mechanisms during temperature cycling

3 Strain relaxation mechanisms during temperature cycling 

It is evident from the discussion presented in Section 7.4 that observation of substrate curvature, interpreted as mean stress in a film bonded to an elastic substrate, during temperature cycling provide a convenient framework with which the inelastic strain relaxation characteristics of thin film materials can be inferred. Indeed, substrate curvature measurement made in the course of temperature cycling is among the most common experimental methods 

The various curvature measurement methods described in Section 2.3 provide convenient tools with which the film stress can be assessed by using the approaches outlined in Chapters 2 and 3 and Section 7.4. However, these approaches are often predicated on assumed microstructural conditions which may differ markedly from real behavior in some material systems. Microstructural evolution and competition between strain relaxation mechanisms can influence the evolution of substrate curvature during thermal excursions and the manner in which such effects are strongly affected by the geometry and material properties of the particular thin film-substrate system being considered. The following points are discussed in order in the remainder of the section, primarily in the context of polycrystalline metal Aims  

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