Ph.D. Projects:
Microstructural design by in situ diffraction during thermo-mechanical processing

Supervisor: Prof. Klaus-Dieter Liss

Scientific Background:

The mechanical and physical properties of materials are strongly influenced by their microstructure, which determines characteristics such as hardness in metallic alloys, electric conductivity, and magnetism. Microstructures are typically developed through controlled materials processing, quenching, and subsequent characterization. This project aims to optimize materials' microstructures using novel in situ neutron and synchrotron X-ray diffraction methods to monitor, in real-time, their phase composition, microstructural arrangements (such as texture, defect concentrations, and grain size), and stress states. Understanding the kinetics and fundamental physics of these processes is crucial for providing parameters for ab initio models.

The materials of interest are refractory metals, which are significant for enhancing efficiency in future thermal energy conversion. Due to their high melting temperatures, alloy and microstructural design are still in early stages, offering potential for development under extreme conditions. Special cases include complex concentrated alloys and high entropy alloys, which often exhibit unprecedented enhanced properties. Additionally, lightweight materials are of interest for reducing energy consumption in the transport and aerospace industries. The novel methods developed will potentially be applied to materials with functional characteristics such as electric conductivity, thermoelectrics, magnetism, or superconductivity.

Beyond conventional processing under mechanical stress and high temperatures, approaches using severe plastic deformation followed by heating will be explored to create fine microstructures with exceptional or novel properties. Ultrasonic and high-frequency methods for processing, fatigue testing, and characterization are also of high interest.

Learning Outcomes:

The goals include a comprehensive understanding of the plastic deformation of materials, precipitation kinetics of secondary phases, defect mechanisms and their role in microstructural evolution, grain refinement and growth mechanisms, and diffusion channels. Additionally, the project will explore the dynamics of materials, transport mechanisms, and the determination of magnetic and other physical properties. High-quality, state-of-the-art scattering and diffraction physics will be applied within a uniform reciprocal space model, supported by knowledge of crystallography. Large data sets will be analyzed using computer scripting and programming, primarily in the Linux operating system. Modern instrumentation will be utilized and understood in detail, with potential development of parts within the project. A broad experience is anticipated, including theoretical foundations, experimental design and setup, applying for beam-time at large user facilities, and conducting experiments. There will be a strong focus on academic output through documentation, presentations in the scientific community, and journal publications.

Desired Skills:

A solid understanding and knowledge of physics or materials science is essential, along with the ability to pursue new and unconventional theoretical and experimental approaches. Knowledge of crystallography, particularly in reciprocal space formalisms, is a plus. Strong computing skills, including scripting and programming with a preference for the Linux operating system, and interfacing with hardware and electronics, are desired. The candidate should be able to search literature, enhance their knowledge, and share it within the research team. Logbook writing and scientific formulation are essential. Good communication and interpersonal skills for operating in a large team, as well as enthusiasm for the work, are expected.

Contact: Prof. Klaus-Dieter Liss, UTK, UT‑ORII. (kdl@utk.edu)

Lab Info: https://volweb.utk.edu/~kliss/

Starting Date: Immediately.