Dear Khaled Adam,
Being retired I cannot claim to be an expert in the field of high entropy (HEntr) alloys. As you characterize your question as 'inquisitive', which I conceive as explorative, I dare to make some tentative remarks.
1. HEntr alloys contain so many different alloying atoms that you can't speak of a base metal. Nevertheless, in many HEntr alloys the alloying elements are all in solid solution. Hence these alloys only consist of one phase.
2. Suppose, the HEntr alloy has only one crystalline phase with all the alloying atoms in solid solution, then the slip systems are in principle given by the type of lattice of that solid solution, e.g. BCC, FCC or HCP.
3. On temperature increase other slip systems may become active, e.g. via cross slip.
4. The activity of the slip systems as indicated by point 2 & 3 may be affected by the composition of the solid solution: are the alloying atoms evenly distributed on the available lattice positions or show they preferences for certain lattice positions?
5. One thing seems me for sure: in case a certain slip system becomes active, it will be that slip system requiring the lowest energy and thus stress. In that sense, it seems that your question already contains its own answer.
Dear Khaled Adam,
As I know, most stable HE alloys have FCC lattice, like CrMnFeCoNi alloy. HCP HE alloy has never been reported so far. The slip system of the HE alloys is {111}, which is the same as most FCC pure metals. However, the stacking fault energy of CrMnFeCoNi alloy is pretty low, so SFs and twins are frequently observed in this alloy.
Thanks, P. Van Mourik and Yang-Tao Zhou for sharing and providing the information.
What is the secret behind the high ductility at low temperature like -180-celsius degree?
Dear Khaled Adam,
Again, I cannot pretend to be an expert in this particular field. Nevertheless, I dare to make the following points/suggestions for further study/research:
1. 'What is the secret behind the high ductility at low temperature like -180-celsius degree?" I wonder if the experimental facts in this question hold for all HEntr alloys.
2. As far as I know, there are indeed FCC HEntr alloys showing high ductility at low temperatures, e.g. minus 180 centrigrades.
3. In metals ductillity is usually provided by dislocation movement supposing sufficient movement of atoms. My first guess would be that at minus 180 centigrades this seems less probable.
4. So other ductility mechanisms should be invoked: e.g. twin formation or gliding along grainboundaries.
5. The consequence of point 4 might be low-temperature ductility depending on the grain size of the HEntr alloy.
Good luck!
Thanks, P. Van Mourik again, it is really helpful,I really appreciated the information you gave me.
Thanks Dierk,
I really appreciate your cooperation in answering my question.
Entropy: A concept that is not a physical quantity
https://www.researchgate.net/publication/230554936_Entropy_A_concept_that_is_not_a_physical_quantity
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