MIXING OF TA-FE AND MO-FE SYSTEMS USING A LOW-ENERGY, HIGH-CURRENT ELECTRON-BEAM

Rutherford backscattering spectroscopy, Auger electron spectroscopy, c onversion electron Mossbauer spectroscopy, transmission microscopy and scanning electron microscopy showed that treatment of a thin Ta or Mo film/alpha-Fe substrate system with a high-current electron beam (HCE B) of an energy density of 2.3-5.2 J cm(-2) resulted in a mixing of th e system's components. In the energy range 2.3-3.3 J cm(-2) in the HCE B-irradiated Ta-Fe system, we found a mixed layer of a thickness of ab out 100 nm, which we relate to the formation of a stable compound (Fe2 Ta, FeTa) and a non-equilibrium Fe5Ta2, compound. The irradiated surfa ce is not uniform, being composed of Ta inclusions of a spherical form (300 nm diameter), solid-solution Fe(Ta) and amorphous-phase Fe-Ta. A n increase in the pulse number results in the formation of the volume fraction FeTa and a dislocation density of 5 x 10(10) cm(-2). It has b een shown that HCEB irradiation of the Mo-Fe system with energy flow d ensities of 2.3-3.3 J cm(-2) produced a mixed layer of a thickness of up to 150 nm, and a non-equilibrium Fe4Mo compound (Fe80Mo20) was form ed. On increasing the energy density to 4.2 J cm(-2), we observed part ial Mo ablation and the formation of a mixed compound with a Mo concen tration of several at.%. (C) 1998 Elsevier Science S.A.