Influence of the variable magnetic field on the corrosive properties of amorphic alloys based on Fe in 0.5 M water solutions H2SO4

Abstract

By chronopotentiometry and cyclic voltammetry methods it was investigated the corrosion resistance of the tape amorphous alloys Fe 78,5 Ni 1,0 Mo 0,5 B 6,0 Si 14,0 and Fe 73,1 Cu 1,0 Nb 3,0 Si 15,5 B 7,4 in an aqueous solution of0,5 M sulfuric acid. The samples alloyed with Cu and Nb showed more corrosion resistance in the aggressive medium of sulfuric acid. Modification of surface of the investigated amorphous samples by an alternating magnetic field leads to an increasing in their corrosion resistance in acidic medium. Surface oxidations in the presence of cuprous and niobium in Fe–Si–B alloy are two-stage processes. In addition of oxidizing Cu in Cu 2 O and sulfates, Nb adsorbs O 2 to form solid solutions of Nb 6 O, Nb 2 O. Oxides with higher oxidation levels (Nb 2 O 5 ) are covalent compounds with low electron conductivity and they can create a passivating superficial layer. In case of amorphous metallic alloys Fe 78,5 Ni 1,0 Mo 0,5 B 6,0 Si 14,0 and Fe 73,1 Cu 1,0 Nb 3,0 Si 15,5 B 7,4 , alternating magnetic field contributes to a significant exit on surface such elements as ferrum and boron (they form the Fe 3 B compound). In the surface layers of the Fe 73,1 Cu 1,0 Nb 3,0 Si 15,5 B 7,4 alloy modified by magnetization, an increase in at. % of Cu, and Nb is observed. Such elements form dense oxide surface protective layers. Weak alternating magnetic field significantly affects not only diffusion, but also the formation of phases in metallic alloys. Thus, alternating magnetic field has a strong influence on the diffusion processes in solid metallic materials, which causes them to homogenize the phases, change the component composition of the domains. These characteristics are directly related to the chemical activity of the surface of metallic materials; therefore, as main instrumental method for testing the effects of alternating magnetic field can be used electrochemical techniques: chronopotentiometry and voltammetry. Keywords : amorphous metallic alloys, corrosion resistance, sulfuric acid, alternating magnetic field.