Nuclear reaction microanalysis of boron doped steels

The microanalysis of trace amounts of boron has been carried out using a 1 μm proton microbeam from the 3 MV single-ended electrostatic accelerator of TIARA facility, JAEA Takasaki. Steel specimens containing 20–100 ppm boron have been bombarded by 1.7 MeV proton beam for γ-ray detection and 1.32 MeV H2+ beam for α-particles. The maps of boron distribution have been measured by detecting 428 keV γ-rays emitted from the 10B (p, α′γ) 7Be nuclear reaction and 3.7 MeV α-particles from the 11B (p, α) 8Be nuclear reaction.As a result of imaging, segregation of several micron sized boron precipitates could be clearly seen.