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Porous anodic alumina films grown in sulfuric acid and similar specimens sealed in nickel acetate and dichromate sealing baths were subjected to a number of surface and bulk analytical techniques (XPS, RBS, SIMS, and XRD). All the oxide films were found to be amorphous‐like in nature, to contain significant amounts of H, and have a S content of 1.5–3 atomic percent (a/o) uniformly distributed throughout the oxide matrices. For the sealed oxide films, surface enrichment of Ni and Cr species was observed, being particularly significant in the case of Ni. Uniform bulk concentrations for Ni and Cr were found to be of the order of 0.5 and 1 a/o, respectively. The S, Ni, and Cr species present in the oxide films were identified as sulfate‐like, nickel hydroxide and dichromate‐like in nature. Ion beam‐induced reduction of incorporated S, Ni, Cr, and C species was observed.

Structural information provided by computed tomography (CT) can be used for quality control and optimization of processes for manufacturing better materials. The squeeze casting method for producing metal matrix composites involves infiltrating a preform of ceramic fibers with molten metal under high pressure. Part quality can be improved if CT is used before infiltration to determine if the preforms have the desired distribution of fibers and are free of defects. Measurements do not require uniform shapes, and CT systems can even be used to obtain accurate densities on complicated part shapes that are not amenable to bulk density measurements based on weight and size. With this quantitative distribution information as a guide, preform production can be modified to produce either a more uniform fiber distribution or to selectively increase the fiber concentration in critical areas. Problems occurring during later stages of processing can be detected in CT images of the completed part. For example. CT can be used to detect unreinforced regions in metal matrix composites caused by cracking of the preform during the squeeze casting process. CT scans of completed parts can also detect and distinguish variations in structure such as microporosity.

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ChemInform Abstract A broad range of surface and bulk analytical techniques, as XPS, RBS, SIMS, and XRD, are applied to Al specimens anodized in H2SO4 and similar specimens sealed in Ni-acetate and dichromate baths. All the films are amorphous in nature and contain C, significant amounts of H and 1.5-3 at.% S distributed uniformly throughout the oxide matrix. Surface enrichment of Ni and Cr species is observed for the sealed oxide films. This enrichment is of particular significance in the case of Ni. The uniform bulk concentrations of Ni and Cr are of the order of 0.5 and 1 at.%, respectively. The various species present in the films are identified as sulfate-like, Ni(OH)2, and dichromate-like in nature. As a result of ion beam-induced surface chemistry, incorporated Cr, Ni, S, and C are also present in lower oxidation states.