The structure–phase transformations and mechanical properties of the shape memory effect alloys based on the system Cu–Al–Ni

Structural and Phase Transformations and Physical and Mechanical Properties of Cu-Al-Ni Shape Memory Alloys Subjected to Severe Plastic Deformation and Annealing

“…As was determined, hot deformation via forging of the studied Cu-based alloys permits refining of austenite grains down to 0.5–1 mm [ 54 , 55 ]. However, the further subsequent cooling in air entails (i) the decomposition by the scheme β→β 1 +γ 2 (at temperatures above the T ED close to 840 K) and (ii) eutectoid decomposition via β 1 →α+γ 2 (at temperatures below T ED ) ( Figure 1 a), which is in good correspondence with the known data from [ 2 , 24 , 35 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 ]. However, quenching of the alloys after their hot forging allows us to prevent the eutectoid decomposition.…”

“…In our works [ 35 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ] it was found that a radical decrease in the grain size during SPD and, accordingly, an increase in the length of the grain boundaries permits us to make the level of embrittlement of SME β-copper alloys lower. Any other methods of refinement of the grain structure of these alloys using alloying additives, heat treatment, rapid quenching, powder metallurgy, and a number of other corresponding methods turned out to be generally unsuccessful [ 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 ].…”

The Effect of Heat Treatment on the Structure and Mechanical Properties of Nanocrystalline Cu–14Al–3Ni Alloy Subjected to High-Pressure Torsion

“…As was previously found [8][9][10][11][12][13][14], under certain conditions, the MPD of eutectoid SME Cu-Al-Ni alloys is the efficient method for radical refining their grain structure and, therefore, plasticization. It is shown in this study that the HPT with high plastic deformations ensures the mechanically induced TMT in the metastable Cu-14Al-3Ni austenitic alloy and simultaneous formation of uniform nanosized UFG structure.…”

“…Results of previous studies showed that the hot forging allows the grain size to be refined to 0.5-1 mm. However, the subsequent cooling of the alloy rods in air leads to the decomposition β → β 1 + γ 2 (at temperatures above T ed that is close to 840 К) and the eutectoid decomposition β 1 → α + γ 2 (at temperatures below T ed ), where the α phase has the fcc lattice and the γ 2 phase is based on the Cu 9 Al 4 intermetallic and has a cubic lattice (D0 3 ) [9][10][11]. The quenching of the alloys after hot forging prevents the eutectoid decomposition.…”

“…deformation (SPD) and, therefore, the increase in the boundary length [8][9][10][11][12][13][14]. At the same time, other various methods used for refining the grain structure of the alloys [15][16][17][18][19][20][21] with application of alloying additions [17,21], heat treatment [15][16][17][18], rapid quenching [6], powder metallurgy and others [19,20], as a rule, were found to be ineffective.…”