Phase transitions during high pressure torsion of Cu Co alloys

The α → ω Transformation in Titanium-Cobalt Alloys under High-Pressure Torsion

“…The torsion torque increased during 1-2 anvil rotations in all alloys and pure Ti and then remained almost unchanged. In other words, it reached a steady state, as was observed previously in other alloys [16][17][18][19][20]51,52]). The central part (about 3 mm in diameter) of each disk after HPT was excluded from further investigations (since it is low-deformed).…”

“…SPD also induces various phase transformations [12] such as formation [13][14][15] or decomposition [16][17][18][19][20] of supersaturated solid solution, dissolution of particles of a second solid phase [21][22][23][24][25][26], amorphization [27][28][29][30][31][32] and nanocrystallization [33][34][35]. Among this variety, very interesting are the phase transformations with formation of high-pressure phases.…”

Microstructural changes in Cu-5.8 at.% In alloy caused by high pressure torsion

“…The lattice parameter of the a-phase (0.364 nm) did not change after HPT and slightly changed for the d-phase It is interesting to note that in the case of the Cu-13.5 at.% In alloy, where volume fraction of d-phase reached the same value (about 20 %) after annealing at 560 8C for 553 h, the HPT process resulted in decrease of crystallite size of a-phase down to 5 nm. Decrease of the a crystallite size from 15 to 5 nm with the increasing indium content was also observed in the Cu -In alloys with 2.3, 4, 5.8, 7, 9.5, and 13.5 at.% In after annealing at 560 8C and HPT processing [10]. So, it can be concluded that the increase in indium content resulted in drastic decrease of the a crystallite size.…”

“…For the Cu -In alloys with 5.8 and 13.5 at.% In annealed at 380 8C for 400 h, the microstructures of the samples were characterised by different volume fractions of the d-phase (about 25 and 50 %, respectively). The subsequent HPT process did not cause the decrease of the a crystallite size due to the same indium content in the a solid solution [10]. Thus, the a crystallite size was influenced by the In content in the Cu-based solid solution and not by the volume fraction of Cu 7 In 3 particles.…”

Microstructural design of new high conductivity – high strength Cu-based alloy

“…The High Pressure Torsion technic would opens up new opportunities. Indeed, as nicely shown by [26] it could be thus possible to control the precipitation state including the size of particle and the composition of the matrix by acting on the rotation angle. The latter control the properties of both strengthening and electrical properties.…”