An Investigation of Sputtered Al-Cu-Fe-Cr Quasicrystalline Films Via Synchrotron Diffraction
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AN INVESTIGATION OF SPUTTERED Al-Cu-Fe-Cr QUASICRYSTALLINE FILMS VIA SYNCHROTRON DIFFRACTION M.J. Daniels1, J. Maciejewski2, J.S. Zabinski3, Z.U. Rek4, S.M. Yalisove1, and J.C. Bilello1 1 Department of Materials Science and Engineering, University of Michigan, 2300 Hayward St., Ann Arbor, MI, 48109-2136 2 Technology Assessment and Transfer, Annapolis, MD, 21108 3 Air Force Research Lab, Wright-Patterson Air Force Base, OH, 45433 4 Stanford Synchrotron Radiation Laboratory, Stanford University, Palo Alto, CA, 94309 ABSTRACT Analysis of the phase relationships of Al-Cu-Fe-Cr based sputtered films, before and after various annealing treatments, was carried out via grazing incidence x-ray scattering (GIXS) at SSRL on beamline 7-2. The “as-deposited” films were composed primarily of nanoscale grains whose structure were mainly quasicrystalline (QC) and its approximants, plus a nano-crystalline phase was also observed in one sample. None of these precursor films exhibited any degree of amorphous character. GIXS studies, in the symmetric and asymmetric modes, revealed that grain growth due to the post-deposition heat treatments caused a decagonal QC phase to evolve and dominate the crystalline phases, which composed the film. These § µm thick films were created by sputter deposition with a DC magnetron source via an Al-Cu-Fe-Cr powder pressed target, giving a nominal sample composition of Al75Cu4Fe8Cr10O3. Two types of annealing treatments were performed using an Argon atmosphere. Anneal of a precursor film for 4 hours at 500°C showed a large fraction of decagonal and approximant phases, while anneal of a precursor film for 2 hours at 400°C and 2 hours at 550°C showed a large fraction of the crystalline phase. INTRODUCTION The evolution of the icosohedral structure in films and bulk materials from the AlCu-Fe system have been studied extensively by a number of authors1,2,3. To a lesser degree, similar studies have been expanded to the decagonal structure in the Al-Cu-Fe-Cr system4,5. However, relatively few studies focus on quasicrystalline films formed from this quaternary system. Quasicrystalline films have the potential for producing surface coatings with low friction and high wear resistance, thus the present study explores the processing conditions for producing reliable QC microstructures. EXPERIMENT Films were deposited at Technology Assessment and Transfer on Inconel and Alumina substrates in a planar magnetron sputtering system under a variety of conditions as listed in Table 1. A powder pressed target was formed from elemental powders to give a target composition of nominally Al84Cu3.5Fe6Cr6.5. Target power was maintained at 600 K8.4.1
Watts and Ar sputter gas was used in all depositions. Sample composition was measured via XPS at the W-P Air Force Research Lab. Subsequent anneals of two of the samples were also performed in an Ar atmosphere. Table 1: Experimental conditions for sputter depositions As-Deposited Annealed Annealed Decagonal + Decagonal Crystalline phase Substrate Inconel Inconel Alumina Ar S
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