The main mechanism for the strengthening of aluminium‐copper alloys of the 2xxx type is hardening by copper‐rich precipitates. However, their size, distribution, and crystal structure determine the final mechanical properties of the material. It has been shown that alloying additionally small amounts of cadmium, indium, or tin influences the precipitation behavior as well as the final strength of Al‐Cu alloys. The binding energy of quenched‐in vacancies to trace elements in the aluminium matrix is recognized as an influence on the diffusion behavior of the copper atoms and thus the preferred type of precipitate changes. A precondition for this influence is the transition of trace elements into solid solution during the solution heat treatment. In the present work, solubility and interaction with quenched‐in vacancies is analyzed for the elements In, Sn, Sb, Bi, and Pb in high‐purity binary alloys using differential scanning calorimetry (DSC), positron annihilation lifetime spectroscopy (PALS) as well as scanning and transmission electron microscopy (SEM, TEM). The results confirm on one hand literature data and deliver on the other hand new structural details. A subsequent anneal at moderate temperature leads to finely distributed precipitations on the nanoscale.

Transmission electron microscopy (TEM) is a widely used tool for analysis of very large scale integrated (VLSI) semiconductor devices. As a special TEM-feature, off-axis electron holography obtains information about the electrical characteristics of a specimen, which are connected to the dopant concentration in the bulk material. Compared with conventional TEM, application of electron holography for dopant profiling demands a higher quality of specimen preparation, e.g. in terms of thickness homogeneity. Since preparation by means of focused ion beam (FIB) has become an industrial standard for TEM-investigations, its facilities are investigated for meeting the high holographic demands. It turned out that, besides many advantages like precision and speed, the use of FIB for preparation introduces new specific problems, e.g. it is hardly possible to visualize doped areas of semiconductors on a classical, thin FIB specimen. Additionally, some artifacts of FIB-preparation have no great importance for normal TEM analysis, but do significantly influence the results of holographic analysis. In order to satisfy the higher demands of preparation for holography, a special procedure for FIB-preparation has been newly developed.

No abstract

No abstract

Nanocrystalline Zn-substituted hydroxyapatite coatings were deposited by radiofrequency magnetron sputtering on the surface of ultrafine-grained titanium substrates. Cross-section transmission electron microscopy provided information about the morphology and texture of the thin film while in-column energy dispersive X-ray analysis confirmed the presence of Zn in the coating. The Zn-substituted hydroxyapatite coating was formed by an equiaxed polycrystalline grain structure. Effect of substrate crystallinity on the structure of deposited coating is discussed. An amorphous TiO2 sublayer of 8-nm thickness was detected in the interface between the polycrystalline coating and the Ti substrate. Its appearance in the amorphous state is attributed to prior to deposition etching of the substrate and subsequent condensation of oxygen-containing species sputtered from the target. This layer contributes to the high coating-to-substrate adhesion. The major P-O vibrational modes of high intensity were detected by Raman spectroscopy. The Zn-substituted hydroxyapatite could be a material of choice when antibacterial osteoconductive coating with a possibility of withstanding mechanical stress during implantation and service is needed.