Project Details
Projekt
Thermodynamics and Kinetics of Ni/Al and Ru/Al Morphologies
Applicant
Professorin Isabella Gallino, Ph.D.
Subject Area
Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
Synthesis and Properties of Functional Materials
Metallurgical, Thermal and Thermomechanical Treatment of Materials
Synthesis and Properties of Functional Materials
Metallurgical, Thermal and Thermomechanical Treatment of Materials
Term
since 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 426208833
The aim of this project is to address open questions regarding the influence of the morphology on the reaction thermodynamics and kinetics of morphologically designed reactive Ni/Al multilayer materials. As a result of the collaboration with the consortium partners, the previous project was able to perform first-time calorimetric investigations of multilayers with different levels of complex geometry and to measure the heat flow during ignition that follows thermal shock. For the first time, the activation energy of the reaction was detected using five orders of magnitude of heating rates, from 0.1 K/s up to 10000 K/s. This was possible by combining differential scanning calorimetry (DSC) with the novel flash calorimetry (FDSC). A novel FDSC methodology to measure free-standing multilayer films was developed and applied, among others to three different systems: (1) planar nanoscaled Ni/Al multilayers with different bilayer periodicities and compositions where a two-stage mechanism for interdiffusion prior to reaction was observed, (2) the synthesis of a B2-structured high entropy alloy films using Ni/Al multilayers as a heat source where the ignition of the reaction was observed in situ in FDSC, and (3) the formation of nickel aluminides from Ni/Al multilayer samples mixed by high-pressure torsion, where we have showed that FDSC can be used to selectively investigate material reactivity at various locations of a single specimen having heterogeneous microstructure. In all these studies, FDSC has proved to be a powerful tool allowing easy access for small specimens at a specific area of a sample and bridging of the gap between slow heating rates of classical calorimetry with the flash rates seen for reactions after ignition. In this project, the newly developed methodology for FDSC will be exploited in order to address the following objectives: (a) characterize the nature of the observed separation of time scale for interdiffusion, (b) determine the effect of 3D complex morphologies on the reaction kinetics for a fixed bilayer periodicity and composition, (c) determine the effect on the reaction sequence and reaction kinetics of the addition of B2-NiAl interlayers to Ni/Al multilayers, (d) the same as above, for Ru/Al multilayers bearing the addition of B2-RuAl interlayers, and (e) extend and apply the FDSC calibration methods for thermal lag and sample mass for complex morphologies of free-standing films in comparison to multilayers directly sputtered on the FDSC sensor. The project plans calorimetric studies of more and more complex morphologies, including 3D morphologies and various complex stacking sequences.
DFG Programme
Research Grants
