The annealing-induced change in the corrosion behaviour of amorphous (Ni0.6Pd0.4)82Si18, (Ni0.4Pd0.6)82Si18 and (Ni0.2Pd0.8)82Si18 alloys was examined together with the irrecoverable relaxation enthalpy (ΔHi,exo). The corrosion resistance based on passivation was significantly enhanced during the initial structural relaxation mostly by the stress release. However, further development of the structural relaxation led to a decrease in the corrosion resistance by the introduction of a chemical heterogeneity in the alloys. Prolonged annealing at lower temperatures was more detrimental than annealing at higher temperatures for a shorter time even if the exothermic values were the same as each other, possibly because the development of long-range groupings of atoms by prolonged annealing was more detrimental than the nucleation of a high density of short-range groupings at higher temperatures. The amorphous (Ni0.4Pd0.6)82Si18 alloy, which had the largest heat of structural relaxation among these three alloys, showed a prolonged enhancement of the corrosion resistance by the initial relaxation, possibly because the beneficial effects of the thermodynamic stabilization, the annihilation of the quenched-in defects and the stress release lasted for a longer time at higher temperatures exceeding the detrimental effect of the introduction of chemical heterogeneity.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry