The focus of this work is the theoretical and experimentell descreption of so-called Reactive Multilayer Systems (RMS). The RMS consist of at least two mostly metallic materials, which can exothermic response with each other. Using magnetron sputter deposition (MSD) several hundred to thousands alternating layers are produced. The periodic thickness varies between 10-150 nm and the total thickness between 10-100 µ m . The exotermic reaction is effected by an activation energy, e.g. with an electric spark. In this case a phase transition of the RMS materials, which are in a metastable equilibrium, will take place. This released energy in the shape of heat, which actvates the reaction in the neighboring areas. It forms a self-sustaining thermal wave through the RMS foil. In this case the amount of energy is present, that a solder on the RMS or the joining samples or even the material itself can be melted. Therefore the RMS can be used as a heat source for joining two components. The major advantage of this technology is the very low heat input in the bonding components, due to the milliseconds of the reaction. Thus the components are heated only superfical and there is no structural damage. Thus a very low-stress joining is possible. Furthermore is guaranteed, because of the metallic materials, a very high electrical and thermal conductivity. For the theoretical characterization of the physical and chemical processes within the RMS FEM-Simulations of the absolut temperature and the propagation velocity are preformed. In order to calculate the tmeperature ditribution in the components a new method will presented. It is thus possible to calculate the temperature penetration of the components to determine potential thermal barrier layer-thickness and the meltig time. Thus parameters for the specific joint problem such as period thickness, etc. of the RMS are derived. Modelling the heat transport after joining with RMS it is possible to derive a corralation between the thermal conductivity and shear strength. To quantify the theoretical results and to require certain parameters for the calculations experiments were preformed. The RMS will be investigated experimentally in terms of their enthalpy H , propagation velocity v , nascent temperature, melting time t schmelz , interdiffusion zone w , phase transition and its use as inovative heat source for joining components. The experimental results are compared with the theortical and complet this work.

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The focus of this work is the theoretical and experimentell descreption of so-called Reactive Multilayer Systems (RMS). The RMS consist of at least two mostly metallic materials, which can exothermic response with each other. Using magnetron sputter deposition (MSD) several hundred to thousands alternating layers are produced. The periodic thickness varies between 10-150 nm and the total thickness between 10-100 µ m . The exotermic reaction is effected by an activation energy, e.g. with an electric spark. In this case a phase transition of the RMS materials, which are in a metastable equilibrium, will take place. This released energy in the shape of heat, which actvates the reaction in the neighboring areas. It forms a self-sustaining thermal wave through the RMS foil. In this case the amount of energy is present, that a solder on the RMS or the joining samples or even the material itself can be melted. Therefore the RMS can be used as a heat source for joining two components. The major advantage of this technology is the very low heat input in the bonding components, due to the milliseconds of the reaction. Thus the components are heated only superfical and there is no structural damage. Thus a very low-stress joining is possible. Furthermore is guaranteed, because of the metallic materials, a very high electrical and thermal conductivity. For the theoretical characterization of the physical and chemical processes within the RMS FEM-Simulations of the absolut temperature and the propagation velocity are preformed. In order to calculate the tmeperature ditribution in the components a new method will presented. It is thus possible to calculate the temperature penetration of the components to determine potential thermal barrier layer-thickness and the meltig time. Thus parameters for the specific joint problem such as period thickness, etc. of the RMS are derived. Modelling the heat transport after joining with RMS it is possible to derive a corralation between the thermal conductivity and shear strength. To quantify the theoretical results and to require certain parameters for the calculations experiments were preformed. The RMS will be investigated experimentally in terms of their enthalpy H , propagation velocity v , nascent temperature, melting time t schmelz , interdiffusion zone w , phase transition and its use as inovative heat source for joining components. The experimental results are compared with the theortical and complet this work.

Cette thèse porte sur la propagation des ondes magnéto-électro-élastiques dans les structures inhomogènes, et tout particulièrement de l’effet d’un champ magnétique externe sur des structures multicouches et des cristaux phononiques combinant des matériaux à la fois piézoélectriques et magnéto-élastiques. Pour déterminer les caractéristiques des ondes se propageant dans ces structures magnéto-électro-élastiques, un modèle de matériau piézomagnétique équivalent à un matériau magnéto-élastique en couche mince, polarisé à saturation autour d’une position d’équilibre définie par l’orientation et l’amplitude d’un champ magnétique externe appliqué à celui-ci, est développé. Il est combiné à une méthode originale de calcul des courbes de dispersion dans les multicouches, basée sur une décomposition en polynômes de Legendre pour les couches d’épaisseur finie, et en polynômes de Laguerre pour le substrat semi-infini. Ce modèle est utilisé pour le cas d’un film mince de TbCo2/FeCo, présentant une anisotropie magnétique uni-axiale dans le plan et une magnétostriction géante, déposé sur un substrat de LiNbO3 sous forme de film ou en réseau de plots cylindriques. On montre que dans ce dernier cas, correspondant à un cristal phononique magnéto-élastiques à résonance locale, il est possible de contrôler sans aucun contact la structure de bande par l’application d’un champ magnétique externe. Ainsi, une sensibilité de 50 kHz par Oersted a été calculée pour une bande plate située dans le gap de Bragg d’un tel cristal phononique. Cette sensibilité est suffisante pour envisager une application du dispositif comme un détecteur très sensible de champs magnétiques localisés / This thesis focuses on the propagation of magneto-electro-elastic waves in inhomogeneous structures, and in particular the effect of an external magnetic field on multilayer structures and on phononic crystals that combine both piezoelectric and magneto-elastic materials. To determine the characteristics of waves propagating in magneto-electro-elastic structures, an effective piezomagnetic material model, equivalents to a thin layer of magneto-elastic material, is developed. The thin layer is polarized to saturation around the equilibrium position defined by the direction and amplitude of an external magnetic field. This model is combined with a method of dispersion curves calculation in multilayer structures, based on a decomposition in Legendre polynomials for layers of finite thickness and Laguerre polynomials for a semi-infinite substrate. The model is used for the case of a TbCo2/FeCo thin film, presenting an in plane uniaxial magnetic anisotropy and a giant magnetostriction, deposited as a film, or as a lattice of cylinders, on a substrate of LiNbO3. It is shown that in the latter case, corresponding to a local resonance magneto-elastic phononic crystal, it is possible to control, without any contact, the band structure by applying an external magnetic field. Thus, a sensitivity of 50kHz by Oersted was calculated for a flat band located in Bragg band gap for such phononic crystal. This sensitivity is sufficient to enable the use of this device as a sensitive detector of localized magnetic fields