1. Heat treatments Produced by Neil Liggett
Aluminium Alloys

2. Aluminium Alloys Solution Heat Treatment
A process in which an alloy or metal is heated to a suitable temperature, is held at that temperature long enough to allow a certain constituent to enter into solid solution, and is then cooled rapidly to hold that constituent in solution.
Definition taken:

3. Aluminium Alloys
When Al / Cu alloys are heated above a certain temperature, the Cu in the alloy goes into what is known as “Solid Solution”. When held at this temperature long enough for the thickness of material all of the Cu will have gone into “Solution”. Hence “Solution Heat Treatment”. At this point the alloy is soft and malleable. Left in this state the alloy will, over time, undergo a “Precipitation” of the solid solution, or “Natural Aging”

4. Composition of Aluminum Alloys Temper (-T) Designations
Aluminium Alloys
Composition of Aluminum Alloys
Alloy
6061-T6
2024-T4
Copper
0.25
4.50
Silicon
0.60
Manganese
Magnesium
1.00
1.50
Chromium
Above indicates percentage of alloying elements in addition to pure aluminum.
Temper (-T) Designations
-T6:
Solution heat treated and artificially aged
-T4:
Solution heat treated

5. Aluminium Alloys
So what are the advantages of aircraft Aluminium Alloys?
Lightweight
Strong
Good Corrosion resistance
Durable – resists loading stresses in
multiple directions
Malleability, easy to form into many shapes
Simple to repair, rivets and
fasteners can be easily removed to replace
damaged parts or sections
Dissipates lightning strikes

6. Aluminium Alloys