Grain-boundary relaxation in copper before and after equal-channel angular pressing and recrystallization

The Effect of Annealing on the Internal Friction in ECAP-Modified Ultrafine Grained Copper

“…processed Cu looks different to that in the non-deformed material: two peaks, denoted as P R and P 3 , can be identified depending on the amount of strain experienced by the specimen and the measurement frequency [1][2][3]. The nature of these peaks is different.…”

“…4a). Earlier, this peak was attributed to primary recrystallization [1,2], the peak (or recrystallization) temperature T R depending on the heating rate. Furthermore, the P R peak is associated with an irreversible increase in Young's modulus (the Köster effect).…”

“…Depending on the frequency, strain and heating rate, the P1 and P2 peaks may overlap [3]: the P2 peak remains symmetrical (Debyelike) only for T above T R [2]. The P 3 peak in ECAP Cu never occurs below the P R peak, in the deformed state.…”

“…The new properties achievable in this way open up novel applications, in particular, in equipment for use at low temperatures down to the cryogenics range. While SPD-processed copper is the most studied material, experimental data on its microstructural stability, particularly with regard to dynamic elastic and dissipative properties at low temperatures, are rather scarce [1][2][3].…”

Internal friction, dilatometric and calorimetric study of anelasticity in Fe–13at.% Ga and Fe–8at.% Al–3at.% Ga alloys

“…Such modulus behaviour may take place in case of recrystallisation (known as Köster effect, e.g. recently reported in [18]), decrease in vacancy concentration or ordering, and ferro-to paramagnetic transition [7]. Similar inverse modulus effect at around 300 • C in Fe-17 at.% Ga alloy was explained by ferro-to paramagnetic transition in paper [4].…”