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A nanomechanical on-chip test platform has recently been developed to deform under a variety of loading conditions freestanding thin films, ribbons and nanowires involving submicron dimensions. The lab-on-chip involves thousands of elementary test structures from which the elastic modulus, strength, strain hardening, fracture, creep properties can be extracted. The technique is amenable to in situ transmission electron microscopy (TEM) investigations to unravel the fundamental underlying deformation and fracture mechanisms that often lead to size-dependent effects in small-scale samples. The method allows addressing electrical and magnetic couplings as well in order to evaluate the impact of large mechanical stress levels on different solid-state physics phenomena. We had the chance to present this technique in details to Jacques Friedel in 2012 who, unsurprisingly, made a series of critical and very relevant suggestions. In the spirit of his legacy, the paper will address both mechanics of materials related phenomena and couplings with solids state physics issues. [ABSTRACT FROM AUTHOR]

Abstract: The remarkable surface properties of quasicrystals have motivated extensive investigations of their intrinsic atomic and electronic structures. In this article, we summarize some of the main conclusions obtained so far. We also describe adsorption experiments where quasiperiodic surfaces are used as templates to grow thin films with novel structures. Finally we discuss some of their useful properties of current interest. [Copyright &y& Elsevier]

Abstract: Owing to their extremely aspect ratios, most thin films are unstable and when they are heated, they will dewet or agglomerate to form islands. This process can occur in the solid state through capillary-driven surface self-diffusion. A key feature of the dewetting process is the retraction of the edges of the film, either natural edges, patterned edges, or edges where holes have formed. Models of edge retraction have been previously developed for isotropic materials and anisotropic materials with differentiable surfaces, but the effects of faceting in highly anisotropic materials have been largely unexplored. Here, we present a two-dimensional model of edge retraction for highly anisotropic, fully-faceted thin films. This model shows generally good agreement with experimental results for edge retraction of single-crystal Ni films on MgO. In both experiments and the model, rims form as the edges retract. The effects of adjusting various physical parameters on the edge retraction rate and the evolving rim geometry were explored using the model. The film thickness, surface self-diffusivity on the top facet of the rim, the equivalent contact angle of the film on the substrate, and the absolute value of the surface energies were found to be the factors that have the greatest influence on the edge retraction rate. In isotropic models and some experimental systems, valleys form ahead of the retracting rims and deepen to contact the substrate and cause pinch-off. Our model suggests that this form of pinch-off will not occur when the rim is fully faceted and the top surface is an equilibrium facet. However, pinch-off can occur through film thinning and for films with top surfaces that do not form flat equilibrium facets. [Copyright &y& Elsevier]

Abstract: We review some models for the dynamics of dewetting of ultra-thin solid films. We discuss the similarities and the differences between faceted and non-faceted systems. The faceting of the dewetting rim leads to corrections in the velocity of dewetting fronts both in flat and axisymmetric geometries. The faceting of the edge of the dewetting rim leads to a strong anisotropy of the dewetting instability. Faceting also induces novel dewetting regimes such as layer-by-layer dewetting, and monolayer dewetting. [Copyright &y& Elsevier]

Abstract: The determination of the separation distance S between the two partials of a dissociated dislocation placed in an elastically anisotropic thin crystal is critically dependent on several parameters: the elastic constants, the Burgers vectors of the partials, the orientation of the fault plane in the crystal, the stacking fault energy per unit surface, the thickness h of the foil and the position of one partial in the crystal. The calculation of S is proposed from (i) an equation expressing the mechanical equilibrium of the two partials and (ii), the knowledge of the displacement field u of an isolated dislocation parallel to the free surfaces of a thin plate-like crystal. Since two theories are available in the literature to express u, both were tested for the calculation of S. One of them was preferred because of its better numerical efficiency and its fully explicit formulation in function of the space variables. This last property permits an easy derivation to be done and is useful to discuss the stability of the mechanical equilibrium of two partials. Numerical applications are presented for a screw dislocation dissociated into two 30° partials, located in a thin face cubic centred Cu-13.43 at.%Al crystal (anisotropy ratio=3.85). Assuming a fixed partial lying in the mid plane of the foil, around which turns a close-packed fault plane, the locus of the other partial is described by polar graphs. These graphs are quite different in the isotropic approximation. To cite this article: R. Bonnet, S. Youssef, C. R. Physique 7 (2006). [Copyright &y& Elsevier]