I have fabricated a multi-material WAAM (TIG-based) sample with alternating layers of 4047 aluminum alloy and ZK61 magnesium alloy. The sample is polished, and I now need to reveal the grain structure:

· Within each individual layer (Al and Mg regions)

· And especially at the interfacial bonding zones between the two alloys

I'm aware that acetic–picral is commonly used for Mg alloys and Keller’s reagent for Al alloys, but since this is a dissimilar metal interface, I'm not sure what etchant (or combination) would work best to bring out both structures clearly under a metallurgical microscope.

· Has anyone worked on similar dissimilar WAAM or weld interfaces?

· Which etchant gives good contrast in both Al and Mg grains?

· Should I etch separately or use a blended approach?

· Any risks of over-etching one side or losing interface detail?

Appreciate any guidance, practical tips, or references!