Hello Ali

read the artical in link

https://materialsdata.nist.gov/bitstream/handle/11115/191/Microstructure%20of%20Alloys.pdf?sequence=3

Hi Ali,

I think the macro-structure in this case might refer to the flow lines. Once the material is deformed, you may be able to trace the flow lines by macro-etching. I personally used Tucker's reagent for the macro-etching of the 7XXX series but I'm not sure about pure Aluminum. On the other hand, the micro-structure, i.e. grains, can be revealed by using a micro-etching reagent like Keller's or Kroll's. These are all I can say based on my experience. You may find better answers for your question.

All the best,

Soheil

ANSI-AWS A3.0-2001 'Stantard Welding Terms and Definitions' says that:

• macroexamination. A metallographic examination in which a surface is examined using no magnification or low magnification.
• microexamination. A metallographic examination in which a prepared surface is examined at high magnification.

MIcrostructure examination include- grains, grain boundaries, some precipitates (require high magnification). Whereas, Macrostructure examination includes- surface examination, machining marks (low magnification)

In the microstructural observation, the grain and grain boundaries are easily seen; so as to, it can be easily predict that, the structure belongs to what type of phase. Whereas, the macrostructure only gives the idea on profile of surface.

Hello Ali

read the artical in link

https://materialsdata.nist.gov/bitstream/handle/11115/191/Microstructure%20of%20Alloys.pdf?sequence=3

Commercial pure aluminium is a non heat treatable metal containing some Fe and Si as gang material. It is strengthened by mechanical working, not by precipitation of phases. Macrostructural studies under optical microscopy up to X25 can reveal only inclusions and overall texture of flow lines in the matrix. At higher magnification with appropriate application of optical microscopy the morphology and texture orientation of the grains alongwith its boundaries can be revealed.

There are many differences base on what you want.

In microstructural studies, grains and grain boundaries are visible if you choose an appropriate etchant. You are also able to see intermetallic compounds depending on the alloy composition.

In macroexamination just a big view is available, etchant differs and also it is possible to study manufacturing process (Casting or wrought).

All depends on what you are searching for.

good luck.

It all depends on how the formation of the primary microstructure begins (chemical individual or Delone simplex) under the influence of the physical characteristics of the external influence (the rate of temperature change during cooling, mechanical shocks, etc.). In this case, the primary microstructure may differ markedly from the initial microstructure.

I think Saham Sharifi gets closer to the answer than most of the other responses.

Everybody seems perfectly clear about what you would be trying to obtain when using micro-examination. However, the answers seem rather more vague when it comes to what you might be looking for with a macro examination. Low-power magnification of surface condition might be one possible option. However, in my experience, the principal time when macro-examination is helpful is when you are (for example) looking to examine the overall configuration of a multi-pass weld in a cross-section from a thick-section plate material (perhaps not very usual in aluminum) or, more probably, you want to examine the structural flow-lines in something like a forged aluminum alloy car suspension wishbone component, where the flow pattern of the material under forging can have a significant influence on its strength in the application.

You simply cannot get the information you need by examining the tiny area of a microstructure sample. What you're trying to do is get your head around the overall structural condition of the component, so you would cut it, grind it reasonably flat, prepare the surface with emery cloth - let's say down to perhaps 800 grit with a paraffin lubricant to remove any surface smearing of the grains due to cutting - then clean it and degrease it thoroughly before etching for long enough that the macro grain structure is revealed. Not just a light etch that you might give to show the microstructure, but a pretty deep etch so that you can even feel the roughness of the surface profile with your nail. Then, with the naked eye, or perhaps a x10 magnifying glass, you can examine the surface to check the grain flow profile over the entire component surface.

Does this example give you a clearer idea of what you are hoping to see when using macro examination?

The answer to the question in this form can be one - an magnification! Depending on the purpose of structural studies, the advice of previous researchers apparently covered a fairly wide range of possible technical and technological tasks.

Soheil Bakhshivash thanks for the response. I think flow lines observation is usually used for detect flow localization in DMM processing maps and it can be one of the applications of macroetching.

Metallographical studies deal with identification of microstructure, grain size, its distribution and grain boundary visualization. Macro-study is performed with naked eye or with low magnification to study the surface defects of an material, whereas microstructural study is to identify the type of structure, grain size, distribution of particles, grain boundaries etc.