Corrosion Resistance of Some Amorphous Metallic Fe–P–M (M = Si, Nb, Mo) Alloys: Effects of Composition, Structural Relaxation, Partial Crystallization, and Local Deformation

Abstract

The corrosion resistance of metallic amorphous alloys (AAs) Fe_80.2P_17.1Mo_2.7, Fe_80.5P_18.4Nb_1.1, Fe_{98 –x}P_xSi₂ (x = 14, 16, 20), Fe_76.5P_13.6Si_4.8Mn_2.4V_0.2C_2.5 in a 0.1 M solution of Na₂SO₄ (pH 6.25) and its change due to structural relaxation, nanocrystallization, and local deformation are studied. The activation of structural relaxation by photonic treatment is shown to increase the corrosion resistance of AAs. As the phosphorus content in the Fe_98 ‒ xP_xSi₂ system decreases, the corrosion resistance of AAs decreases because of partial crystallization, which is accompanied by the formation of iron phosphides during rapid cooling of a melt, and silicon segregation at phase boundaries. The formation of local deformation zones in the near-surface layer of Fe_76.5P_13.6Si_4.8Mn_2.4V_0.2C_2.5 AA decreases its corrosion resistance. The niobium alloying of Fe‒P AAs is shown to be effective to decrease the corrosion rate.