AVS 50th International Symposium
    Thin Films Wednesday Sessions
       Session TF1-WeA

Paper TF1-WeA8
Preparation of Ternary Alloy Libraries for High-throughput Screening of Material Properties by Means of Thick Film Deposition and Interdiffusion: Benefits and Limitations

Wednesday, November 5, 2003, 4:20 pm, Room 329-

Session: Thin Film - Based Combinatorial Methods
Presenter: A. Rar, Oak Ridge National Laboratory and The University of Tennessee
Authors: A. Rar, Oak Ridge National Laboratory and The University of Tennessee
E.D. Specht, Oak Ridge National Laboratory
E.P. George, Oak Ridge National Laboratory and The University of Tennessee
G.M. Pharr, Oak Ridge National Laboratory and The University of Tennessee
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Numerous techniques have been developed for making ternary alloy libraries for combinatorial materials development. Two popular approaches for synthesizing films are: (i) co-deposition from 3 different pure element sources and (ii) preparation of multilayer thin films with thickness gradients in different directions for each component, followed by annealing of the films to achieve local alloying. However, both methods have limitations. In the first, the elemental distribution is non-linear, the film thickness is not constant, and regions with low concentrations of one or more elements are difficult to achieve. In the second approach, synthesis of thick films may be a problem because of the large numbers of layers required. One possible solution is to deposit a single relatively thick layer for each element, followed by annealing to achieve alloying. This approach was examined for the Ni-Fe-Cr ternary system. Spatially resolved alloy properties were compared with well known structural properties by means of rapid XRD mapping with synchrotron radiation. Specimens were prepared by depositing films onto sapphire substrates with an e-beam evaporation system. After deposition, the layers were interdiffused by annealing in different environments. The quality of the resulting specimens was examined using cross sectional SEM, electron microprobe analysis, angular resolved x-ray fluorescence, and XRD. The main problems were encountered during annealing. Selection of annealing temperatures and times that could be used to produce good interlayer diffusion without Cr evaporation or Kirkendall voiding proved difficult. In addition, there was a tendency to form chromium oxide at the surface. Despite these problems, an isothermal section of the ternary phase diagram was reasonably well reproduced.