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In this paper, the influence of microstructure on the corrosion behavior of a hot-extruded 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 β' martensite and (α+Κ_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 hot-extruded material since the volume fraction of β' phase which was anodic to α 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 different roles in the mechanical properties and corrosion resistance of the experimental alloy.