During normal cross-section preparation, no corrosion of the metals such as Al or Ti occurs. Corrosion is only possible if the sections are etched after polishing. You can only do this etching very briefly (a few seconds), then you can get good pictures of the weld.

Thank you for your suggestion. In my experiment, the specimens were mechanically ground with 320#, 1200#, 3000#, and 7000# SiC sandpaper, and then the samples were polished with the liquid MgO suspension, and finally etched in a solution of 20 mL acetic acid, 20 mL water, 8 g picric acid, and 150 mL ethanol. During the final etching process, the two phases cannot be clearly visible at the same time.

To obtain clear metallographic photos of dissimilar metals like aluminum (Al) and titanium (Ti) with different corrosion resistances, follow these effective steps:

These methods will help you achieve clear metallographic images of both phases.

@Ze Deng,

Please follow the following laboratory processes

Prepare samples according to acceptable standards ASTM precisely.

Hot or cold mounting using please get appropriate resin

Grinding using silicon carbide papers with different grit sizes (400 to 6000).

Polishing operation for 80 seconds @ 175 rpm.

Second level polishing with colloidal silica suspension (5 μm)

Perform chemical etching with 2% HF acid for 5 s.

Examination of the microstructures could be performed using a metallurgical microscope

For corrosion products you can subject the samples to corrosion environment such as 3.5 %NaCl or 3.5 % NaOH

Use the metallurgical microscope to observe and produce the images.

Thank you