TEM Foil Preparation from Irradiated Metallic Materials: A Practical Approach

Abstract

This paper focuses on work related to post irradiation examination of 300-series austenitic stainless steel taken from reactor vessel internals of PWR. High neutron irradiation dose in NNP's leads to a degradation of microstructure of the material in a nano-metric scale. Hence, it is important to characterize the irradiated materials to understand the physical basis of the degradation mechanisms. Microstructural characterization of neutron-irradiated materials by TEM requires enhanced sample preparation methodologies, which commonly needs general improvements regarding particular experiment to be performed. In this study, the authors have developed methodology specialized in 1 mm TEM thin foil preparation from a deformed shank of a broken miniaturized tensile specimen. TEM foil size in current studies is smaller than standard because of the small shank diameter and high radioactivity of the studied material. The reduction of the TEM foil radioactivity to minimum is crucial to perform EDX chemical analysis and to increase the EDX detector lifetime. This paper describes whole process from bulk sample handling, including remote-controlled material cutting in shielded hot-cells and disc polishing in glow-boxes, up to the final procedure of electrolytic-polishing of electron transparent 1 mm TEM foils. Eventually, results of TEM microanalysis of radiation-induced defects were present.

Optimization of Surface Properties for Nanoindentation Studies on Nuclear Structural Materials

“…Thus the method permits to study how the mechanical properties correlate to the level of damage on the nuclear structural materials [1][2][3]. To perform analysis on the irradiated specimens at nanoscale, sample preparation should be well optimized to reduce surface defects, art effects and minimize the surface roughness from metallography to ensure high quality of results [4].…”

“…The main aim in this work is to obtain minimal roughness/mechanical damage of surface from the metallographic processes that ensures reliable results in nanoindentation experiments and minimizes the indentation size effect. Also the procedure should be well adaptable for the sample preparation in hot-cells for understanding the mechanical behavior of neutron/ion irradiated materials and reproducible [4,6]. Metallographic sample preparation was performed using various methods from standard to state-ofthe-art devices to optimize the surface roughness.…”