PhD Project by Yi-Chieh Yang
Project Title: Study of materials’ structure under non-equilibrium conditions using in-situ EM
Group: Nano-Micro-Macro. Structure in Materials
Supervisor: Joerg Jinschek
Project Description
Transmission electron microscopy (TEM) has become a powerful and indispensable tool for material characterization and chemical analysis at the (sub-)nanometer length scale. To study thermally activated structural processes or reactions in materials, such as melting, phase transformation, recrystallization, grain growth, sintering, decomposition of compounds, the stress in thin films or at interfaces etc exploiting a TEM’s spatial resolution, special in-situ stages have been developed. Since the early 1960s, based on published literature, the characterization of materials using in-situ heating inside a TEM has been applied. With the introduction of MEMS-technology, utilizing a fine control of temperature set point and ramping rate, as well as a very low power consumption mitigating sample drift, in-situ heating experiments can now precisely be performed.
In this project, we will use the state-of-the-art MEMS-based TEM heating stages to investigate the solid/solid interface stability under thermal gradient. The stages can generate fast ramping of temperature (in the range of 10,000K/sec), as well as thermal gradients in the range of > 10,000K/m. These capabilities can be utilized for simulating the process and operating conditions of materials in many applications in the in-situ TEM experiments, such as the additive manufacturing (AM) processing conditions. By the technique, we aim at obtaining a depth understanding of non-equilibrium process conditions and their effect on the resulting microstructure in the material. Additionally, we also plan to utilize electron microscopy fundamentals to measure the actual temperature (gradient) of the specimen itself to confirm our findings.
Group: Nano-Micro-Macro. Structure in Materials
Supervisor: Joerg Jinschek
Project Description
Transmission electron microscopy (TEM) has become a powerful and indispensable tool for material characterization and chemical analysis at the (sub-)nanometer length scale. To study thermally activated structural processes or reactions in materials, such as melting, phase transformation, recrystallization, grain growth, sintering, decomposition of compounds, the stress in thin films or at interfaces etc exploiting a TEM’s spatial resolution, special in-situ stages have been developed. Since the early 1960s, based on published literature, the characterization of materials using in-situ heating inside a TEM has been applied. With the introduction of MEMS-technology, utilizing a fine control of temperature set point and ramping rate, as well as a very low power consumption mitigating sample drift, in-situ heating experiments can now precisely be performed.
In this project, we will use the state-of-the-art MEMS-based TEM heating stages to investigate the solid/solid interface stability under thermal gradient. The stages can generate fast ramping of temperature (in the range of 10,000K/sec), as well as thermal gradients in the range of > 10,000K/m. These capabilities can be utilized for simulating the process and operating conditions of materials in many applications in the in-situ TEM experiments, such as the additive manufacturing (AM) processing conditions. By the technique, we aim at obtaining a depth understanding of non-equilibrium process conditions and their effect on the resulting microstructure in the material. Additionally, we also plan to utilize electron microscopy fundamentals to measure the actual temperature (gradient) of the specimen itself to confirm our findings.
Contact
Yi-Chieh Yang PhD student
Contact
Joerg R. Jinschek Professor