Study on additively manufactured Al-Mg-Sc-Zr alloy with low Sc/Zr ratio for marine environments
Researchers from Indian Institute Of Technology DelhIi and m4p material solutions GmbH, Feistritz, Austria, have published a study in Materials Letters investigating the corrosion behaviour of additively manufactured Al-Mg-Sc-Zr alloy with a Sc/Zr ratio of less than 1 in 3.5wt% NaCl solution.
X-ray diffraction (XRD) analysis revealed the presence of an Al matrix with a face-centred cubic (FCC) structure and the secondary phase Al3(Sc,Zr) with an L12 crystal structure. Microstructural analysis indicated a bimodal grain size distribution with fine equiaxed and columnar grains influenced by thermal gradients and secondary phase Al3(Sc,Zr). Potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) tests in 3.5wt% NaCl solution demonstrated that the alloy exhibits a less negative corrosion potential and lower corrosion current density compared to other Al-Mg-Sc-Zr alloys with higher Sc/Zr ratios, indicating superior corrosion resistance.
The researchers attributed the enhanced performance of the 3.5wt% NaCl solution to the fine grain structure and the formation of a stable protective oxide layer facilitated by the higher Zr content.
