Morphological characterization, in vitro biomedical corrosion and corrosion behaviour of As-Cast Cu-Zn-Al-FeMn alloys in selected intravenous and industrial fluids

Several research findings have been published on the influence of grain size control additives on the structure-property relationship and performance of Cu-Zn-Al Shape Memory Alloys. However, a wide knowledge gap still exists between the findings on the ordinary Cu-Zn-Al alloys and their shape memory counterparts. Herein lies a significant contribution that addresses this issue. Cu-Zn-Al and FeMn-modified Cu-Zn-Al alloys of preferred chemical compositions were developed by stir sand casting. The alloys were prepared for and subjected to metallographical and corrosion immersion tests in sulphate-containing, chloride-containing and designated physiological environments. Experimental results showed FeMn to be an effective inoculant for heterogeneous nucleation and crystal growth in Cu-Zn-Al alloys. Modified grains with different sizes and morphologies were observed. There also appeared to be a Hall-Petch kind of relationship between corrosion resistance and grain size of the FeMn-modified alloys in nearly all the corrosion media. Dezincification of the FeMn-modified alloys was significantly facilitated with high Zn content and large grain size, notably in the sulphate-containing environment. Nonetheless, the dramatic difference in the corrosion behaviour of Cu-Zn-Al alloy and that of FeMn-modified Cu-Zn-Al alloys in the corrosion media only occurred at the initial stage of experiment. Thereafter, a stable corrosion behaviour was observed for the FeMn-modified alloys. (paper)