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Example of AES

The Auger process allows the emission of kinetic energy by secondary electrons.  The identity of an element of a material's surface can be verified by knowing the kinetic energy that is emitted and analyzing the intensity of Auger peaks.  A study performed at the Department of Biomaterials in the University of Gothenburg [1] applies Auger Electron Microscopy (AES) to samples fabricated using Electron Beam Melting (EBM).  EBM is a technology originally developed by Arcam AB (M?lndal, Sweden) to create functional parts through the use an electron beam gun which melts metal powder deposited in a layer-by-layer fashion according to a CAD file. 

In this study, AES was utilized to analyze surface properties to determine if the samples produced by EBM are within the specifications for surgical implant applications.  The study used a PHI 660 scanning auger microprobe at energy of 3.0keV to analyze six implant specimens created using powder of a titanium alloy (Ti6Al4V). Additional parameters used by AES were a beam current of 400nA, an area of analysis of 150µm in diameter, a resolution of 0.6%, spectrum width of 30-1080eV, 5 scans at each point, and utilizing an analysis time of 50ms/eV.  The samples produced as well as the zones measured by AES are shown in Figure 1 (5 different points in each zone were measured).  Samples that were machined to achieve a better surface finish were compared to samples that were fabricated and processed directly from the machine.


The results of this study are given in Table 1 and show that the implants produce are within the specifications for surgical implant applications.  A discrepancy shown by AES was the appearance of a 2.1%Fe in one of the samples which may have appeared from a post-processing step of EBM.  One of the non-machined samples analyzed also contained a notable oxide layer that can particularly affect the achievement of bone growth.  It was therefore concluded that depending on the surface preparation techniques and processes used, additive manufacturing technologies such as EBM can be used to customize and produce implants for living organism.




References:

[1]      Thomsen, P., Malmstr?m, J., Emanuelsson, L., Rene, M, Snis, A., (2008). Electron Beam-Melted, free-form-fabricated titanium alloy implants: Material surface characterization and early bone response in rabbits.  Journal of Biomedical Material Research Part B: Applied Biomaterials, 90 (1), pp. 35-44.