Einfluss von Spannung und Verformung auf die Phasenbildung in reaktiven Ni/Al Multischichten
Zentrum für Mikro- und Nanotechnologien
This project aims at identifying the effects of mechanical and thermomechanical stresses and constraints on the transformation reaction and phase formation in transformation imprinted materials. This includes intrinsic and extrinsic stresses resulting from mechanical loading as weil as stresses caused by geometrical confinements, such as passivation layers on multilayer films. As shown for various metal combinations, intrinsic stresses may affect the thermodynamics, which might be used to obtain metastable phases and microstructures. Whether similar effects can be observed under mechanical loads is the central question to be addressed by this project. The findings should be used to design and control the phase morphologies and microstructures. Moreover, new or metastable phases and new process paths should be identified. The following factors affecting the phase transformations will be studied: (i) stress and deformation through external loads using different loading conditions, including uniaxial tensile loading, bending, compression and contact loading, (ii) internal stress caused by external confinements. Nanoscale metallic multilayer films on substrates will be used as model materials. The occurring intrinsic stresses will be further evaluated by thermomechanically coupled numerical simulations and parameter identification by inverse modelling through a close collaboration with project P1. Figure P4.1 gives a graphical summary of the project. This project will answer the question of the influence of applied mechanical and thermomechanical stresses on the phase formation and stability at different temperatures for different morphologies and microstructures as weil as on the self-propagating transformation. lt contributes in cooperation with other projects to the development of models for the prediction of transformation imprinted materials and to a successful microjoining process.