Abstract: This HREM investigation focuses on the influence of point defects on the final epitaxial relation and atomic interface configuration in a CoSi2/Si(1 0 0) heterostructure. A two-step SPE-MBE grown CoSi2/Si(1 0 0) system is used and, by altering the number of deposited Co monolayers in the template layer, the point defect behavior is studied. We propose a film growth model in which the knowledge about the reconstructed (2 x 1) : Si(1 0 0) surface, the point defect behavior in the presence of an interface, especially a silicide interface, the migration of point defects through a lattice by formation of [1 0 0]-split interstitial (dumbbell) atomic configurations, and a new type of extended defect configurations in diamond type materials will all amalgamate. (C) 1998 Published by Elsevier Science B.V. All rights reserved.

Abstract: The phase transformation sequences during thermal decomposition are investigated for Ni-rich melt-quenched body-centred cubic (bcc) and amorphous Ni-Zr alloys. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) are used to determine the structure of crystallization products occurring after heating the melt-spun ribbon samples to various degrees of the phase transformation process monitored by differential scanning calorimetry (DSC). A single DSC peak is observed for both the bcc and amorphous Ni(91)Zr(9) alloys and a two-step process is indicated by DSC for the amorphous Ni(90)Zr(10) alloy. In the bcc-Ni(91)Zr(9) alloy which is actually a Ni(Zr) solid solution phase, the phase transformation starts with the precipitation of Ni(5)Zr crystallites followed, after a sufficient depletion of the matrix in Zr, by the subsequent transformation of the bcc-Ni(Zr) lattice to face-centred cubic (fcc) Ni. In the amorphous alloy of the same composition, the final products are fcc-Ni and Ni(5)Zr but at intermediate stages of the phase transformation, bcc-Ni(Zr) crystallites also appear. In the a-Ni(90)Zr(10) alloy the first DSC peak corresponds to the formation of the bcc-Ni(Zr) phase which then decomposes (second DSC peak) to the equilibrium phases fcc-Ni and Ni(5)Zr. Thus, in addition to the previous observation of the formation of the metastable bcc-Ni(Zr) phase by rapid quenching from the melt, here we present evidence that this phase can form also after partial crystallization of metallic glasses of appropriate chemical compositions.