Strengthening In Aluminum Alloys

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In summary, the conversation discusses the relationship between grain size and mechanical properties in metals. It is agreed that smaller grain size generally leads to increased strength due to impeded dislocation motion. However, there is a disagreement over the effectiveness of this mechanism in Al alloys compared to steels. The professor argues that in Al alloys, particle strengthening is the dominant factor and grain size has little effect. The conversation ends with a recommendation to consult a book on aluminum for further discussion on this topic.
  • #1
Rasputin
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Hi everyone!

I have a question about mechanical properties of the materials. As I understand, when in metals microstructure the grains size decreases, the mechanical properties increases, specially metals strengthening.
But I have a discussion with one Prof. who says that this is a minor eefect in Al alloys as compare to the steels. In Al only an Orowan mechanism works. In this mechanism, the dislocation bends between the particles leaving a dislocation ring about each particle.

Is he right? Anyone can help me to find the strengthening mechanism in metals.

Thanks a lot.
 
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  • #2
Your understanding is correct; grain size influences yield strength. (Anything that impedes dislocation motion in ductile polycrystalline materials increases strength.) However, perhaps your professor is saying that in a particular alloy, particle strengthening is so effective that changing grain size has little effect. Do you know what alloy he or she had in mind?
 
  • #3
He means all kinds of aluminium as compare to steel where grain size have a big influence to its mechanical properties.
 
  • #5
Rasputin,

Your professor must be nuts! When grains get down to the sub-micron level grain size most certainly will effect yielding. Dislocation pileup is a real effect and has been observed on TEM. Making blanket statements like that in Material Science is wrong!

modey3
 
  • #6
Modey3, Thanks, I got this book and seems very good with good theories and their explaining.
 

1. What is strengthening in aluminum alloys?

Strengthening in aluminum alloys is the process of increasing the strength and hardness of aluminum alloys through various methods such as alloying, heat treatment, and mechanical processing.

2. Why is strengthening important in aluminum alloys?

Strengthening is important in aluminum alloys because it improves the mechanical properties of the material, making it more resistant to deformation and able to withstand higher loads and stresses.

3. What are the different methods of strengthening in aluminum alloys?

The different methods of strengthening in aluminum alloys include precipitation hardening, solid solution strengthening, work hardening, and grain refinement.

4. How does precipitation hardening strengthen aluminum alloys?

Precipitation hardening involves heating the alloy to a high temperature and then rapidly cooling it, which causes fine particles of a second phase to form within the alloy, increasing its strength and hardness.

5. What are the advantages of strengthening aluminum alloys?

Some advantages of strengthening aluminum alloys include improved mechanical properties, increased wear resistance, and better corrosion resistance, which can result in longer-lasting and more durable products.

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