No REX in HEA at high temperature?
No REX in HEA at high temperature?
(OP)
I am working now on a high-entropy alloy which seems not to recrystallize at high temperature annealing (>0.5Tm).
It is hot forged and has grains of few tens of um with many nanocells inside them. At high T it seems that grains are growing but not recrystallizing and dislocations remain stable but change their arrangement into more equilibrium state.
My question is: do you have any ideas about this kind of phenomenon? Are there any materials which have similar properties? It seems very bizarre...
It is hot forged and has grains of few tens of um with many nanocells inside them. At high T it seems that grains are growing but not recrystallizing and dislocations remain stable but change their arrangement into more equilibrium state.
My question is: do you have any ideas about this kind of phenomenon? Are there any materials which have similar properties? It seems very bizarre...





RE: No REX in HEA at high temperature?
RE: No REX in HEA at high temperature?
I also found this high density of disocations in Al alloy AA1235 after annealing... It was explained by nanoprecipitations blocking dislocations movement. My idea for now are nanofluctuations of chemical composition, and in case of HEAs this effect may be strengthened by lattice distortion and sluggish diffusion.
And are you sure that REX is not possible in this state? It seems that at lower T, around 600C (~0.4Tm) new grains are present in the structure... How can I explain that? In my opinion there is some change of phenomenon at around 0.5Tm...
RE: No REX in HEA at high temperature?
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P.E. Metallurgy, Plymouth Tube
RE: No REX in HEA at high temperature?
RE: No REX in HEA at high temperature?
And how would you explain that at low temperature (<0.5Tm) this mechanism seems to be different and there are small REX grains (or at least free of dislocations)?
And what about still very high density of dislocations after long heat treatment at T>0.5Tm? Isn't recovery about decreasing density of dislocations?