Abstract
Abstract Nickel-aluminum bronze (NAB) alloys are suitable, in cast condition, to be used in marine propellers due to its excellent behavior avoiding erosion and cavitation as well as corrosion. A complex microstructure, intrinsic to this copper base system, is the result of a well-controlled chemical composition. There are few works related to the effect of adding small quantities of specific chemical elements on NAB alloys properties. The aim of this paper is to study the effect of Ti on the microstructure, mechanical properties, and corrosion behavior of a particular NAB alloy, CuAl10Fe5Ni5 (C95500), and the comparison to the Ti-free NAB alloy. Although the as- cast microstructure is very similar for both materials, the addition of only 120 ppm Ti leads to a significant grain refinement that plays a key role on the mechanical properties. It has been observed an increase in both microhardness and nanohardness as well as in the resultant Young moduli values, meanwhile no significant impact on the corrosion susceptibility has been observed.
Highlights
Nickel-aluminum bronze alloy (NAB) is a copper-based alloy, which contains aluminum, nickel, iron, manganese, and other minor elements
Polarization resistance (Ω.cm-2) 2.4x105 2.1x105. It has been presented a comparative study between two different NAB samples with a slightly change on chemical composition based on the addition of 120 ppm of Ti
The Scanning Electron Microscope (SEM) images, Energy Dispersive X-ray detector (EDX) and X-ray diffraction (XRD) results have shown the presence of different kappa intermetallic compounds in each sample with different chemical compositions
Summary
Nickel-aluminum bronze alloy (NAB) is a copper-based alloy, which contains aluminum, nickel, iron, manganese, and other minor elements. It is widely used in marine engineering applications such as marine propellers, valves, etc. The main reason for the high corrosion resistance of NAB alloys has been related to the development of a protective layer of around 1 μm in thickness, rich in aluminum and copper oxides[8], that is firmly adhered to the base material, and providing low corrosion in natural water. Zhang et al.[11,12] showed that selective corrosion is highly dependent on the pH and a corrosion wear mechanism was proposed, concluding that the tribocorrosion behavior of NAB alloy in seawater is closely related to the halide-ion concentration
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