Bulk Diffusion of Homovalent Atomic Probes of Scandium, Lanthanum and Thorium in Single Crystals of Tungsten
The volume diffusion of nonmagnetic homovalent atomic probes (APs) from the IIIB group of the periodic table of the elements (PTE)Sc, La, and Th in Whas been studied by the method of secondary ion mass spectrometry. The Arrhenius dependences have the following parameters: the coefficients DSc - (D0)Sc = (1.4 0.3)10-4 m2s-1 and QSc = (546±4) kJ/mole; the coefficients D¬La - (D0)La = (1.6 0.8)×10-6 m2s-1 and QLa = (41010) kJ/mole; and the coefficients DTh - (D0)Th = 4.4×10-6 m2s-1 and QTh = 447 kJ/mole. It has been found that the coefficients D5dAP(Tm)W of the bulk diffusion of transition 5d APs in W coincide at its melting point (Tm)W. The enthalpies, QWSc,La,Th, of the volume diffusion of nonmagnetic homovalent APs from the IIIB group of PTE increase linearly with decreasing relaxation volumes, , of these APs, which interact with vacancies in W. The sums, (Q + E)WSc,La,Th, of the bulk diffusion enthalpies, QWSc,La,Th, and the relaxation energy, (E)WSc,La,Th, of the environments of homovalent APs diffusing to W are nearly constant.
David J. Fisher
S.M. Klotsman et al., "Bulk Diffusion of Homovalent Atomic Probes of Scandium, Lanthanum and Thorium in Single Crystals of Tungsten", Defect and Diffusion Forum, Vols. 305-306, pp. 1-13, 2010