In-situ scanning Kelvin probe force microscopy on the diverse hydrogen trapping behaviours around incoherent NbC nanoprecipitates

One of the most intriguing methods of mitigating the hydrogen embrittlement of steels entails nanoprecipitates that can trap H from enriching at vulnerable locations. However, controversial findings have been reported on whether the incoherent NbC precipitates trap hydrogen. Here, by using in-situ scanning Kelvin probe force microscopy (SKPFM), we reveal the dynamic interaction of H with the border area of incoherent NbC nanoprecipitates in steel. Results indicate that the interaction between H flux and the interfaces varies amongst different precipitates, implying that H-trapping behaviours of incoherent NbC precipitates could be intrinsically diverse. Potential origins underlying the distinct behaviours are analyzed.