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Nanostructured Fe-18Cr-2Si alloys were developed by a combination of mechanically alloying (MA) and spark plasma sintering (SPS) process. SPS was carried out in vacuum at three different temperatures (900, 1000, and 1100 °C) with a fixed holding time of 10 min and an applied pressure of 50 MPa. Potentiodynamic polarization (PDP), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) were used to study the effect of sintering temperature on the electrochemical properties of newly developed nanostructured ferritic Fe-18Cr-2Si alloy. XRD results showed that, after sintering, crystallite size increased with increasing sintering temperature and maximum crystallite size was 23.64 nm. The results showed that with increasing sintering temperature, corrosion resistance was increased in terms of pitting potential (Epit), passive current density (ip), and polarization resistance (Rp). The improved corrosion resistance was found to be closely related with the densification of the sintered alloys. [ABSTRACT FROM AUTHOR]

Laser controlled melting of metal surface provides a local treatment with improved surface properties such as corrosion resistance. In the present study, laser surface treatment of iron base superalloy (A286) is carried out. The corrosion resistance of the laser-treated surface is examined through potentiodynamic tests using 0.5 N NaCl solution. The microstructural and morphological changes in the laser-treated layer are investigated incorporating scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy. The residual stress formed at the laser-treated surface is measured using the XRD technique. It is found that laser treatment enhances corrosion resistance of A286 superalloy surface, which is attributed to the formation of fine grains and dense layer at the treated surface. Although locally scattered few corrosion induced microcracks are observed at the treated surface, they are not extended to form large cracks or crack network at the surface. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]