L. Pasquini

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Publications (2)0 Total impact

  • Article: Thermal vacancy formation and D0_ {3} ordering in nanocrystalline intermetallic (Fe_ {3} Si) _ {95} Nb_ {5}
    L. Pasquini
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    ABSTRACT: The correlation between thermal vacancy characteristics and D03 ordering in ball-milled nanocrystalline (Fe3Si)95Nb5 was studied by combined measurements of x-ray diffraction and positron annihilation. Structural stabilization due to grain boundary segregation of Nb enables high-temperature positron lifetime measurements up to 1023 K from which vacancy formation parameters identical to those in single-crystalline D03 Fe3Si are deduced. Measurements of coincidence Doppler broadening show that prior to the onset of thermal defect formation in the nanocrystallites, positrons are annihilated in Nb-enriched grain boundaries. The D03 ordering of the initially disordered Fe3Si nanocrystallites is discussed on the basis of the thermal vacancy characteristics and self-diffusion behavior.
    Phys. Rev. B. 63(13).
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    Article: Thermal vacancy formation and D03 ordering in nanocrystalline intermetallic (Fe3Si)95Nb5
    L. Pasquini, A. A. Rempel, R. Würschum, K. Reimann, M. A. Müller, B. Fultz, H. E. Schaefer
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    ABSTRACT: The correlation between thermal vacancy characteristics and D0(3) ordering in ball-milled nanocrystalline (Fe3Si)(95)Nb-5 was studied by combined measurements of x-ray diffraction and positron annihilation. Structural stabilization due to grain boundary segregation of Nb enables high-temperature positron lifetime measurements up to 1023 K from which vacancy formation parameters identical to those in single-crystalline D0(3) Fe3Si are deduced. Measurements of coincidence Doppler broadening show that prior to the onset of thermal defect formation in the nanocrystallites, positrons are annihilated in Nb-enriched grain boundaries. The D0(3) ordering of the initially disordered Fe3Si nanocrystallites is discussed on the basis of the thermal vacancy characteristics and self-diffusion behavior.
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