In the work, we studied structural phase states in surface layers of electron beam-irradiated nickel-titanium (NiTi) alloy depending on beam energy density. The surface of NiTi specimens was exposed to pulsed irradiation (pulse duration tau = 150 mu s, number of pulses N = 5) by a low-energy high-current (I = 70 A) electron beam with surface melting at electron beam energy densities E-1 = 15J/cm(2), E-2 = 20 J/cm(2), and E-3 = 30 J/cm(2). The surface layer structure was examined by X-ray diffraction analysis and transmission electron microscopy. It is found that in the NiTi specimens irradiated at E <= 20 J/cm(2), the layer that contains a martensite phase resides not on the surface but at some depth from it. In the NiTi specimens irradiated at E3 = 30 J/cm2, the entire modified surface zone is characterized by a two-phase state in which the B19' phase dominates over the B2 phase. It is supposed that a barrier to B2 -> B19' martensite transformation in the melted NiTi layer irradiated at E <= 20 J/cm(2) is high inhomogeneous residual stresses varying with depth from the irradiated surface. (C) 2014 Elsevier B.V. All rights reserved.