Influence of electron beam liquid phase surface treatments on the corrosion resistance of AZ91D using different additive deposition techniques

• Electron-beam alloying and cladding were applied successfully on the Mg alloy AZ91D.
• The AlSix additive deposition technique influences alloyed-layer quality strongly.
• Low oxygen contents in the deposition layers result in homogeneous alloyed layers.
• The hardness of defect-free layers is increased up to three times compared to AZ91D.
• The corrosion behaviour is improved greatly compared to the untreated base material.

Electron beam alloying (EBA) and electron beam cladding (EBC) were applied on AZ91D using Al-based additives. For EBA, additives were pre-deposited by atmospheric plasma spraying (APS) and cold gas spraying (CGS). In the case of EBC, a wire was used for in situ additive deposition. Polarisation test were carried out to investigate the corrosion behaviour of layers with Mg-rich (EBA) and Al-rich (EBC) layer matrices depending on the element contents of Mg, Al, and Si. In 0.001 M NaCl solution, the corrosion potential is significantly improved compared with the untreated AZ91D and corrosion current densities of the AlSi12 reference material are approached.