[EvaH (OP)]

Enix asks:

I would like to ask a question regarding aluminium. Please tell me what strengthens/weakens aluminium and what is the difference from aluminium used on cans vs aluminium used on alloy wheels(mag wheels)?

Can you help?

[alancalverd]

There are many commercial alloys of aluminium with a huge range of properties. https://en.wikipedia.org/wiki/Aluminium_alloy lists a few hundred, principally divided into "casting" and "wrought" materials.

The physical properties of an alloy depend considerably on the grain size, which is determined by the additives (principally silicon and various metals) and forming process.   

[evan_au]

what strengthens/weakens aluminium

With most pure metals (and aluminium is a good example), bending first hardens it, then weakens it.
- A pure, single-crystal metal tends to be fairly soft: the atoms are all the same size, and the planes of atoms can slide over each other fairly easily
- When you bend it (work hardening), the planes of atoms break (dislocations), and this prevents further sliding.
- If you keep bending it, these dislocations grow into a fracture, which weaken the metal, and eventually cause it to break. 

See: https://en.wikipedia.org/wiki/Work_hardening
https://en.wikipedia.org/wiki/Fatigue_(material)

what is the difference from aluminium used on cans vs aluminium used on alloy wheels(mag wheels)

Aluminium cans are designed to be as thin as possible - just enough to withstand the pressure of the gas inside, and the weight of cases of cans piled on top of each other.
- They need to be bent into shape, so you want something that is very soft - pure aluminium meets this requirement

Aluminium wheels are designed to withstand the weight of a car, impacting potholes in the road, so it is a lot thicker.
- By mixing other metal atoms in with the aluminum to make an alloy, the atoms are no longer the same size
- The atoms do not form neat planes, so they can't slide over each other
- This makes an alloy much harder than a pure metal

For an idea of how bendable and stretchable pure aluminium is, see:

[hamdani yusuf]

Gallium can make aluminum weaker.

[evan_au]

Gallium can make aluminum weaker.

...or does the aluminium make the gallium stronger?

[hamdani yusuf]

Gallium can make aluminum weaker.

...or does the aluminium make the gallium stronger?

It can be both ways. But since in the video the quantity of aluminum is mich higher than the gallium, then it's normally said that in this case, Gallium make aluminum weaker.