Methode zur quantitativen Auswertung der Röntgen-Kleinwinkelstreukurven von geschmolzenen binären Legierungen

Abstract

A method is given for calculating from the absolute intensities of the X-Ray small angle scattering the concentration and atomic composition of clusters in binary molten alloys. For the alloy with 30 a/o Sn and 70 a/o Al it is shown that at least two models exist. A decision between these two models cannot be given at the moment.First model: Particles consist of tin atoms only. Mean particle distance 28 to 36 Å. Diameter of particles 10 Å. Density 6.5 g/cm3. Particle concentration in the melt 2.42 a/o. Mean atomic weight of the matrix atoms 52.89. Density of matrix 3.97 g/cm3. 28.27 a/o of the matrix consist of Sn, 71.73 a/o of Al. 27.58 a/o of the Sn is contained in the matrix.This model is in agreement with the measured increase of cluster diameter with increasing tin concentration.Second model: Particles consist of Al atoms only. Mean particle distance 18 to 23 Å. Diameter of particles 10 Å. Particle density 2.37 g/cm3. Particle concentration in the melt 7.56 a/o. Mean atomic weight of the matrix atoms 56.74. Density of matrix 4.17 g/cm3. 32.45 a/o of the matrix consist of Sn, 67.55 a/o of Al. 62.44 a/o of the Al is contained in the matrix.This model is in agreement with the phase diagram. In this case, the Al-clusters would be preformed nuclei in the melt which lead to primary precipitation of pure aluminum during the solidification process.