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In recent years, the study of renewable energies and its practical application has increased significantly. Solar energy feasibility entails the development of energy storage systems since solar power plants need to be working in unfavorable weather or night periods. The main heat transfer fluid (HTF) used on these plants is a salt mixture of 60% NaNO3/40% NaNO3 which must be kept above 220 °C to prevent freezing. This high operating temperature causes corrosion problems for steels in contact with the HTF, reducing the lifetime of the solar plants. The present research studies the potential of an alumina‐forming austenitic (AFA) stainless steel (OC‐4, Fe‐25Ni‐14Cr‐3.5Al‐2.5Nb wt% base) as a candidate material for solar plant heat exchangers and pipes. Corrosion behavior of OC‐4, relative to 304 stainless steel and T22 steel, was studied by gravimetric analysis and electrochemical impedance spectroscopy (EIS). The AFA OC‐4 exhibited better corrosion resistance in HTF at 390 °C than the currently used 304 austenitic stainless steel.

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Nanoindentation tests of Pd 40 Cu 30 Ni 10 P 20 bulk metallic glass were performed over a wide range of indentation rates (from 0.04 up to 6.4 mN s −1 ) under the standard load control mode. New results using the feedback displacement control mode are also presented. The dependence of the pop-in formation on the loading rate is investigated. Variations in hardness and reduced elastic modulus as a function of the indentation rate are observed. A softening effect occurs when increasing the loading rate. This is explained by the differences in plastic deformation achieved at different indentation rates. The displacement control mode was used to avoid the shear localization of the free volume, leading to the almost complete absence of pop-ins along the loading curve. The obtained results suggest that plastic flow in bulk metallic glasses is governed by the rate of creation of free volume, which depends on the strain rate and its localization into shear bands.

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