Preparation of ternary alloy libraries by means of thick film deposition and interdiffusion: structure and mechanical pr
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Preparation of ternary alloy libraries by means of thick film deposition and interdiffusion: structure and mechanical properties A. Rar1,2, E. D. Specht1, H. M. Meyer III1, M. L. Santella1 , E.P. George1,2, and G. M. Pharr1,2 1 2
Oak Ridge National Laboratory, Metals and Ceramics Division, Oak Ridge, TN The University of Tennessee, Department of Materials Science and Engineering, Knoxville, TN
A method of preparing ternary alloy libraries for combinatorial materials development based on thick film deposition and interdiffusion was studied, using the Ni-Fe-Cr ternary system. Specimens were prepared by depositing films onto sapphire substrates with an e-beam evaporation system followed by annealing in a vacuum for interdiffusion. The specimens were examined using cross sectional scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) , scanning Auger microanalysis (SAM), angular resolved x-ray fluorescence (AR-XRF), x-ray diffraction (XRD), and nanoindentation. The method proved an effective way to make the alloy libraries for screening mechanical properties by means of nanoindentation.
I. INTRODUCTION The development of the methods for high throughput analysis of binary, ternary, and quarternary alloys is a subject of great interest in materials science [1]. The main issues limiting wide application of combinatorial methods to alloy design are: (i) effective preparation of alloy libraries; (ii) how well the libraries reproduce the relevant properties of the bulk materials; and (iii) how the properties of these libraries can be rapidly assessed. Here, we investigate one way to achieve this using Ni-Fe-Cr as a model ternary alloy system. This system was selected because it is the basis of a wide variety of commercially important alloys such as stainless steel. As such, it has been extensively studied, and the structure and properties are well known. In this paper, we describe methods of the library preparation by means of thin film deposition and interdiffusion and briefly discuss results of the library characterization by means of SEM, SAM, AR-XRF and scanning XRD. The possibility of screening the mechanical properties of the alloys by means of nanoindentation is demonstrated.
II. EXPERIMENTAL Specimens of Ni-Fe-Cr were prepared by depositing films onto 5 cm diameter circular sapphire substrates followed by annealing in vacuum to interdiffuse the layers. Substrates with three different orientations were used: (0001), (112 0), and (1 1 02 ) . The latter two orientations were found to suppress texture formation and therefore simplify structural analysis by x-ray diffraction (XRD). Metal deposition was performed in an electron beam evaporation system equipped with a sliding shutter and a sample rotation stage. A typical background pressure was about 10-6 Torr, and the deposition rate measured with a quartz microbalance was approximately 3 nm/sec for Cr and 0.3 nm/sec for Fe and Ni. Layers of Cr, Fe and Ni were sequentially deposited using the sliding shutter to create a thickness gradien
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