Phase analysis of surface layers irradiated with high-energy electron beam using Mِssbauer spectroscopy

The phases present in the surface layers of a plain carbon steel, a gray cast iron, and a TiB2/steel surface-alloyed material irradiated with high-energy electron beam were analyzed by Mössbauer spectroscopy in conjunction with the microstructural observation. When the plain carbon steel with ferrite–pearlite structure was irradiated with an electron beam, the pearlite region was transformed to martensite, while the ferrite region to bainite. In the case of the gray cast iron, the surface was melted and transformed into a mixed structure composed of ledeburite eutectic structure and of retained austenite. The surface layer of the TiB2/steel surface-alloyed material consisted of the melted and the transformed regions. The structures of both regions were identified to have ferrite–bainite–pearlite mixed structures from the Mössbauer analysis. The Mössbauer analysis data matched well with the microstructural observations of the irradiated surface layers, confirming that the Mössbauer analysis is quite useful in interpreting phase transformation upon electron beam irradiation.