Micro-Portion Image Analysis of Light Elements in Fe–Cr Based Alloys by Time-of-Flight Secondary Ion Mass Spectrometry

Abstract

The mechanical properties of high-alloyed steels are influenced by small amounts of light elements such as hydrogen, carbon, and nitrogen, which are dissolved or precipitated. Thus, it is important to analyze the microscopic distribution of these light elements in the microstructure of steels. Secondary ion mass spectrometry (SIMS) is a powerful method for detecting the distribution of light elements in the microstructure of steels. In this study, time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to analyze the microscopic distribution of light elements, such as deuterium, carbon, and nitrogen in Fe–Cr based alloys which are typical high-alloys, as ToF-SIMS provides high sensitivity and high spatial resolution. The studied Fe–Cr based alloys were a pure ferritic Fe-10%Cr alloy and a commercial duplex stainless steel consisting of the ferritic and austenitic phases. Both steels were electrochemically charged with deuterium. The results showed that charged deuterium more easily diffuses out of the ferritic Fe-10%Cr alloy in comparison with the duplex stainless steel, and small amounts of carbon and nitrogen were segregated at grain boundaries in Fe-10%Cr. It was also shown that deuterium, carbon, and nitrogen were heterogeneously distributed in the microstructure of the duplex stainless steel.