Debye temperature of disordered bcc-Fe-Cr alloys

الأصل · EN

Debye temperature, TD, of Fe100-xCrx disordered alloys with 0<x<99.9 was determined from the temperature dependence of the centre shift of 57Fe Mossbauer spectra recorded in the temperature range of 80-300K. Its compositional dependence shows an interesting non-monotonous behaviour. For 0<x< 45 as well as for 75<x< 95 the Debye temperature is enhanced relative to its value of a metallic iron, and at x= 3 there is a local maximum having a relative height of 12% compared to a pure iron. For 45<x< 75 and for x> 95 the Debye temperature is smaller than the one for the metallic iron, with a local minimum at x= 55 at which the relative decrease of TD amounts to 12%. The first maximum coincides quite well with that found for the spin-waves stiffness coefficient, D0, while the pretty steep decrease observed for x> 95 which is indicative of a decoupling of the probe Fe atoms from the underlying chromium matrix is likely related to the spin-density waves which constitute the magnetic structure of chromium in that interval of composition. The harmonic force constant calculated from the Debye temperature of the least Fe-concentrated alloy (x>99.9) amounts to only 23% of the one characteristic of a pure chromium.