Why is Phase/Microstructure Analysis Important?
- These components of your metals/alloys/coatings, etc.
control their mechanical/chemical properties and behavior.
When you do surface modification and/or coating, you may
affect the starting microstructure (in some cases this may
be done intentionally).
- Additionally, the interface between a coating and substrate
may determine the success of the coating, or be the source
of a failure, if not properly engineered and managed.
Etchants for Aluminum Alloys.
- Al alloys containing Cu, Mn, Si, Mg, Ti. Cast Al alloys
with high Si content.
Hydrochloric Acid (1.19 N) - 75 mil
Nitric Acid (1.40 N) - 25 mil
Hydrofluoric Acid (40%) - 25 mil
(seconds to minutes exposure)
- Al Alloys - most types, especially containing Cu
Distilled water - 75 mil
Nitric Acid (1.4 N) - 25 mil
Heat to 70 degrees C (160 degrees F)
40 seconds exposure
Etchants for Steels and Cast Iron
- Nital - most common etchant for steels and
gray cast irons:
- Ethanol or Methanol (95%) - 100 mil
Nitric Acid (1.40 N) - 1 to 10 mil
(but do not exceed 10 mil)
Seconds to minutes exposure.
- Murakami's Reagent - used to highlight
carbides (in some alloys may be stained
- Distilled water - 100 mil
- Potassium or Sodium Hydroxide - 10 g
- Potassium Ferricyanide - 10 g
(concentration is variable)
2 to 20 minutes exposure 20-50 degrees C
(70-120 degrees F) temperature solution
(Use only fresh solution).
- Examples of polish/etch interactions:
Available in our Gallery, the micrographs show the
importance of sample preparation/etchant effects,
etched colored structures, and a combination of
SEM/surface chemical analysis to identify phases.