The behaviour of freely suspended smectic-C* ( SmC(*)) films at the bulk SmC(*)-cholesteric ( N(*)) phase transition has been investigated using polarized-reflected-light microscopy. Our experimental observations show that above the bulk SmC(*)- N(*) phase transition the N(*) order appears in different ways according to the film thickness. In thin films, the conventional layer-by-layer thinning occurs. In films of intermediate thickness N(*) inclusions nucleate inside the SmC(*) film. The distortions of the in-plane orientational order of the SmC(*) host phase induce elastic interactions between the inclusions and lead to their self-organization in chain-like structures. Both the dynamic of the chaining and the parameters driving the equilibrium distance between the inclusions in the chain are investigated. In thick films, N(*) fingers grow inside the film. The influence of the experimental conditions on the various processes is analysed.

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 18105To link to this article : a b s t r a c tThe crack growth behaviour of Direct Aged Inconel 718 was studied at 550°C. Experiments were carried out under pure fatigue cycles, hold-time cycles of different durations and a mix of both. Hold-time cycles were systematically associated with complex crack front morphologies. A new numerical approach was developed to assess the effect of crack front morphology on the direct current potential drop technique, mechanical fields at the crack tip and ultimately, measured crack growth rates. Using this approach, a clear relation was established between crack front morphology and its evolution, and the crack growth behaviour under hold-time conditions. Complex crack front morphologies are demonstrated to be responsible for increased crack growth rates. From this, a crack growth mechanism under hold-time conditions is proposed. Finally, the numerical framework here presented is to be considered as a new, easily reproducible, way to properly analyse experimental data when dealing with complex loading cycles and complex crack front morphologies.⇑ Corresponding author at: Safran Aircraft Engines, établissement de Villaroche,