M.Sc. Dennis Langenkämper
Dennis Langenkämper started his PhD in Dezember 2015 at the Lehrstuhl Werkstoffwissenschaft (WW) at Ruhr-Universität Bochum. Main object is to explain the relation between microstructure and martensitic phase transformations in high temperature shape memory alloys (HT SMAs). The effects of local alloy chemistry and crystallography including point defects, dislocations and precipitates will be studied using transmission electron microscopy (TEM). His Research will first focus on promising polycrystalline Ti-Ta based alloys as well as on Co-Ni-Ga. Dennis Langenkämper uses advanced TEM to study elementary transformation and deformation processes. The microstructural evolution during processing will be documented (ingot metallurgy: melting and forming, thin film technology: sputtering and heat treatment). Special emphasis will be placed on the evolution of the microstructure during the repeated exploitation of the mechanical and thermal shape memory effects (functional fatigue). In addition, the oxidation behavior of Ti-Ta based alloys will be addressed. This includes the formation of oxide layers and the evolution of surface zones of the alloy next to the oxide. The role of the evolving surface layer alloy compositions on the martensitic transformations will also receive attention.
- relation between microstructure and martensitic phase transformation in Ti-Ta-X and Co-Ni-Ga HTSMA
- transmission electron microscopy (TEM)
- oxidation behavior of HTSMA based on Ti-Ta