I am working on Al 5059/Al2O3 composite fabrication using Friction Stir Processing
Dear Sandeep
It is depend what you want to reveal:
for: Examination for solid-solution coring or segregation and diffusion effects
4 g KMnO4, 2 g Na2CO3, 94 mL H2O, a
few drops wetting agent
Specimen surface must be well polished and precleaned in 20%
H3PO4 at 95 °C (205 °F) for uniform wettability. After precleaning,
rinse in cold water and immediately immerse in etchant for 30 s.
Examination for preferred orientation
(Barker's
reagent)
4 to 5 mL HBF4 (48%), 200 mL H2O Electrolytic: use aluminum, lead, or stainless steel for cathode;
specimen is anode. Anodize 40-80 s at approximately 0.2 A/cm2 (1.3
A/in.2, or about 20 V dc). Check results on microscope with crossed
polarizers.
or
50 mL Poulton's reagent (etchant 4 in
Table 1), 25 mL HNO3 (conc), 40 mL
of solution of 3 g chromic acid per 10
mL of H2O
Put a few drops on as-rolled or as-extruded surface for 1-4 min,
rinse, and swab to desmut. Examine on microscope with crossed
polarizers to show grains. Repeat etching, if necessary. For some
5xxx alloys, increase HNO3 in solution to 50 mL.
It is from Metals handbook
Good luck
Belma
You can etch the 5059 aluminium alloy as the closely related 5083 alloy: https://www.researchgate.net/post/What_is_the_suitable_etchant_required_to_visualize_the_grain_boundaries_of_an_aluminium_5083_alloy
A- The most common etchant solutions for aluminum are Kellers etch and Kroll's reagent.
B- There are hundreds of more specific etchant solutions for Al-Alloys.
C- A good resource for additional etchant solutions can be found with the etchant database provided by PACE Technologies:
http://www.metallographic.com/Consumables/Etch.htm
D- The Table attached below show the best etchant solutions for Al-Alloys.
Try concentric Keller's reagent (25 ml HNO3, 15 ml HCl, 10 ml HF and 50 ml H2O). Etch until clear grain structure is revealed. Etching time can vary between 20s to 5 mins to obtain clear structure.
Hello Sandeep!! The ASTM standard E407-07 for etching alloy 5XXX is detailed in the given paper. Have it for your reference!!
Article Modelling Corrosion Behavior of Friction Stir Processed Alum...
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