Dear All,
I have a sample, the composition is a mixture of Al-Cu-Fe. I need to use Argon gas or Fermi gas during annealing to avoid sublimation and oxidation. Which one is better? Also I should say that Al has evaporate during annealing.
Cheers
Dear Hadi,
The Fermi gas is a model in physics doing reference to a gas of fermions and it is not a real gas for thermal treatments. I suppose that you are talking about a mixture of gases (4-6% Hydrogen in Nitrogen) which some companies distribute under the trade name of FORMIER Gas.
Argon is a standard in thermal treatments, but usually it contains some ammount of water vapor and at high temperature could react with you alloy producing some oxidation. Sublimation or evaporation would be related to a low pressure of Argon or in a constant gas flux treatment. You may use very high purity Argon practically at atmospheric pressure, but this will become expensive.
You may also use FORMIER Gas, which is also used for thermal treatments in steels to avoid oxidation. It is a good reductor gas to avoid oxidation and could work well in your alloy. At the normal concentration of Hydrogen the gas mix is not flamable, but must be carefully manipulated (send you a data sheet). However if you may use it in a closed enclosure will be a good protection against oxidation, but you have to take care about the further ventilation of the enclosure.
I hope this could be helpful for you.
Kind regards,
Jose SAN JUAN
It depends on the purity of argon used, I recommend you to use ultrapure argon like Alphagaz 2. What's your temperature of treatment?
Kind regards,
Abdel Ait Chaou
I think argon gas is fit for your experiment. Being not known your mixture of Al-Cu-Fe, weather it is by mechanical alloying, just like ball milling alloying or other way. If not have nanoparticls, ordinary purity argon can meet the requirements of your experiment. Using a mechanical pump, after evacuation, argon gas rushed into the heat treatment furnace several times. If have the nanoparticls, you may need the Ultrahigh vacuum heat treatment furnace.
From annealing point of view a mixture of hydrogen( a higher proportion) and nitrogen is more desirable.
As the Aluminum alloys usually are very Oxidation Sensitive and even commercially pure Argon gases contain a little fraction of Oxygen, I highly recommend you use Vacuum furnace for heat treatment. Alternatively, as Mr. Abdelouahed Ait Chaou said, you should use high purity Argon. in the latter case, i think it is better to use a graphite basket/box to provide semi-reductive atmosphere and avoid oxidation of Aluminum.
Water must be eliminated to the greatest degree. Notice that water may attain up to about 5 ppm for low purity grade commercial Ar, while for higher purity grade the humidity content will not exceed 0.5 ppm. Further drying can be considered, with drying agents as CaH2, Mg(ClO4)2, P2O5, or by using molecular sieve.
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