Our research foucuses on the relationship between structure and properties and how they relate to the processing and application of materials, and involves the use of different analytical and electron optical techniques for the identification and characterization of different features in a material's microstructure on the micro, nano and atomic scale.The main tecniques used are:
- Scanning electron microscopes (SEM) with add-ons such as energy dispersive X-ray spectroscopy (EDX), electron back-scatter diffraction (EBSD) and low-loss backscatter electron imaging using an energy selective backscatter (ESB) detector.
- Transmission and scanning transmission electron micsroscopy (TEM/STEM) with EDX, EELS and HAADF.
- 3D atom probe tomography (APT) using voltage and laser pulsing
- Site specific TEM and APT specimen preparation using focussed ion beam (FIB) milling technique.
The research can be divided into four main areas:
We study the mechanisms behind the degradation of high temperature materials such as nickel based bulk alloys and coatings, steels and FeCrAl alloys. The important phenomena to understand are: oxidation, corrosion and cracking of the materials during their use. The investigations are done using state-of-the-art experimental techniques (transmission electron microscopy, atom probe tomography…) for the characterisation of the material structure and chemistry down to nearly atomic level, and the work is performed in collaboration with the High Temperature Corrosion Center at Chalmers and with Swedish industry.
We study the development of the detailed microstructure of hard materials during production and service, and how the microstructure determines primarily mechanical properties like hardness, wear resistance and toughness. In particular we study grain and phase boundary chemistry and structure, mechanisms of grain growth inhibition, mechanisms of high-temperature deformation, and solid solution hardening of hard and binder phases. Materials studied are primarily cemented carbides (hard metals), cubic boron nitride, wear resistant coatings and ceramics, and extensive collaboration with the cemented carbide industry and thermodynamic and atomistic modeling is made.
We study the mechanisms of degradation of materials used in light water nuclear reactors, such as zirconium alloys, nickel-based superalloys, austenitic stainless steels and reactor pressure vessel (RPV) steels . The microstructure of oxide layers formed in water on zirconium alloys, and of the metal/oxide interface zone, is characterized in great detail using TEM and APT, in order to understand the rate limiting process for oxygen transport and hydrogen pick-up. The microstructure of oxide layers on superalloy X-750 is studied as a function of flow rate, metal and water composition. The effect of thermal aging and irradiation on the microstructure and properties of RPV welds is studied mainly using APT.
We study functional materials, that posses native properties or functions which are utilized in a component or application. The functional materials studied in the Division may find applications in information and communication technology, energy generation and storage, transport, and healthcare. This is a quickly expanding research area within the Division of Materials Microstructure. A recent example is the study of implant/bone interfaces.