The Special Features of the Phase Formation and Distribution in the Titanium Nickelide Surface Layers Treated by Electron Beams

摘要

The special features inherent in the formation of the structural-phase states on the surface of titanium nickelide samples subjected to multiple low-energy high-current variable energy density pulsed electron beam irradiation are investigated. The parameters of the electron beam operated in the fivefold surface melting regime are as follows: pulse duration tau = 150 mu s, current I = 70 D, and energy densities D center dot (1), D center dot (2), and E (3) = 15, 20, and 30 J/Nm(2), respectively. The surface layer structure was examined by methods of the x-ray diffraction analysis and transmission electron microscopy. It is found that in the irradiated TiNi samples with D center dot a parts per thousand currency sign 20 J/Nm(2), the layer containing a martensite phase lies at a certain depth below the surface rather than on the surface. In the irradiated TiNi sample with E (3) = 30 J/Nm(2), the subsurface region is in a two-phase state (B2 + B19'), with the D'19' phase being predominant. It appears that the lower is the energy density, the smaller is the amount of the martensite phase.