Effect of microstructure on the mechanical and corrosion behaviors of a hot-extruded nickel aluminum bronze

Abstract

In this paper, the in∞uence of microstructure on the corrosion behavior of a hotextruded nickel aluminum bronze was studied. Three kinds of samples subjected to the hot-extrusion, annealing and quenching conditions were prepared and immersion tests in 3.5% NaCl solution were carried out. Microstructures and corrosion surface morphologies of the samples were observed by SEM. It was found that the retained fl 0 martensite and (fi+•III) lamella eutectoid in the as hot-extruded material were eliminated after annealing, and corrosion resistance of the alloy was improved. As to the as-quenched material, its corrosion rate was higher than that of the as hotextruded material since the volume fraction of fl 0 phase which was anodic to fi phase increased after quenching. As regards the mechanical properties, the as-quenched sample possesses the highest hardness and tensile strength among the three kinds of samples, while the as-annealed sample possesses the highest elongation. That is to say, heat treatment plays difierent roles in the mechanical properties and corrosion resistance of the experimental alloy.