PSI - Issue 83

Daniele Cortis et al. / Procedia Structural Integrity 83 (2026) 3–13 9 shows that a small serration can be observed transiently after the yielding point [Ning et al. (2026)]. The mechanical properties show a slight increase: about +5% for the YS and UTS, up to ≃ 435 MPa and ≃ 520 MPa respectively. The A remains almost unchanged, within the accuracy confidence level. On the other hand, at high temperatures (+100 °C and +200 °C) the quick recovery and dislocations annihilation reduce the interaction between solute atoms and dislocations [Ning et al. (2026)], eliminating the PLC effect, see Fig. 5 (c) and Fig. 5 (d). At +100 °C, the YS and UTS are reduced, with respect to room temperature, of about -10%, while the A increases of about +60%. However, at +200 °C the material progressively loses its strength: the YS drops to ≃ 185 MPa (- 55%), while the UTS falls to ≃ 190 MPa (-60%). Finally, the A shows an average value of 10%. As expected, the elastic behavior of the material changes with temperature, as shown in Fig. 6 (a). At room temperature (+22 °C), the E is in the range of 60-65 GPa, as expected for this kind of alloy, while with decreasing temperature (-100 °C), it shows a slight increase up to 68 GPa. Finally, at high temperatures (+100 °C and +200 °C), it decreases to ≃ 62 GPa and then falls at ≃ 46 GPa respectively. Differently, the ν shows the opposite trend, decreasing at low temperature and increasing at high temperatures Fig. 6 (b). At room temperature (+22 °C), it has the expected value in the range of 0.33-0.34, while at -100 °C it drops to ≃ 0.32 and at high temperatures (+100 °C and +200 °C), it rises to ≃ 0.35 and ≃ 0.40. Consequently, G shows the same behavior of the material elasticity, increasing with temperature (Table 4). These results clearly highlight the operational limits of the material, demonstrating that in the range of ±100 °C, it possesses high strength and good stability of mechanical properties, due to the presence of Al 3 (Sc,Zr) nano particles within the α (Al) matrix. However, at high temperatures (+200 °C), its strength is extremely low, making its use inadvisable.

(a) ε ' = 0.00025 s -1

(b) ε ' = 0.00025 s -1

Serration

PLC (Type A)

(c) ε ' = 0.00025 s -1

(d) ε ' = 0.00025 s -1

Fig. 5. True-strain ( ε *) vs true-stress ( σ *) curves at different temperatures: (a) -100 °C; (b) +22 °C; (c) +100 °C; (d) +200 °C.