Non-metallic inclusions in copper and copper alloys

In this study, industrial copper and copper alloy samples were investigated with regard to non-metallic inclusions. Different types of inclusions (exogenous and endogenous) were detected and investigated with regard to appearance and chemical composition. It was observed that inclusions tend to accumulate and are often surrounded by pores. The most frequently exogenous inclusions found in the industrial samples consist of silicon dioxide, silicon carbide and carbon inclusions. Endogenous inclusions were mostly detected in aluminum-containing alloys whereby the inclusions were present as oxide films. Initial attempts to artificially introduce non-metallic inclusions into copper melts revealed significant challenges, including floating of these inclusions due to density differences and poor wetting behavior. Finally, filtration trials of aluminum-containing copper alloys via ceramic foam filters revealed a remarkably higher proportion of oxide film structures above the filter and its entry compared to the filter exit, indicating the effective removal of such structures. These findings highlight both the complexity of inclusion behavior in copper alloys and the potential of ceramic foam filters for their mitigation.