INDENTATION RESISTANCE AND CORROSION BEHAVIOUR OF Fe-Mn MODIFIED Cu-Al ALLOYS IN SELECTED INDUSTRIAL AND BIOLOGICAL FLUIDS

Abstract

The hardness, and corrosion behaviour of ferromanganese modified Cu-Al alloys in selected industrial and biological fluids has been investigated. Cu-Al alloys containing approximately 12wt% Al were produced by casting with varied lean additions of ferromanganese ranging from 0.1 – 0.4 wt% of the charge. The alloys were thermo-mechanically processed adopting a homogenization – cold rolling- annealing treatment as part of the alloy design schedule. Hardness measurement, weight loss corrosion testing and microstructural analysis were used to characterize the alloys produced. The results show that the addition of ferromanganese led to partial refinement of the grain structure with inequigranular recrystallized grains manifesting as dispersed phase in the Cu-Al alloy matrix. The hardness of the Cu-Al based alloys was observed to generally improve with the addition of Fe-Mn although it did not show sensitivity to increase with corresponding increase in the wt% of Fe-Mn. The mass loss of all grades of the alloy produced were observed to be less than 0.02g/cm2 in NaCl solution. In H2SO4 solution, it was observed that the addition Fe-Mn to the Cu-Al based alloys resulted in distinct improvement of the corrosion resistance of the alloys. The corrosion rates were also relatively lower in glucose and dextrose and saline solutions (<0.006g/cm2) in comparison with NaCl solution (<0.02g/cm2). It was noted that additions of 0.1-0.2wt% Fe-Mn to the Cu-Al based alloy yielded the best combination of properties in the study.