Particle Stimulated Nucleation Effect for Al-Mg-Zr-Sc Alloys with Ni Addition during Multidirectional Forging

Abstract

The study aims to investigate the influence of fraction of coarse undeformed particles on the microstructure evolution and mechanical properties of alloys processed by isothermal multidirectional forging (MDF). For this purpose, Al-Mg-Ni-Sc-Zr-based alloys with different Ni concentrations and a fraction of Al3Ni particles of solidification origin phase were subjected to MDF at 350 °C. Precipitates of the L12-structured Al3(Sc,Zr) phase retained their structure, morphology, and size after MDF and were coherent with the aluminum matrix. The Al3Ni phase particles stimulated the nucleation of recrystallized grains and contributed significantly to the formation of an ultrafine-grained structure. The uniformity of the grain structure increased, and the average grain size decreased with an increase in the fraction of Al3Ni particles. A fine-grained structure with a mean grain size of 2.4–3.4 µm was observed after MDF with a cumulative strain of 12. The results demonstrate that a bimodal particles size distribution with a volume fraction of nanoscale f~0.1% and microscale f~8% particles provided for the formation of a homogenous fine-grained structure after MDF and improved the mechanical properties.

Microstructure Evolution and Constitutive Modelling of Deformation Behavior for Al-Mg-Si-Cu-Sc-Zr Alloy Processed with Isothermal Multidirectional Forging

“…The increase in cumulative strain and MDF temperature resulted in an increase in particle distribution homogeneity. The homogeneously distributed microscale particles can contribute to grain refinement during thermomechanical treatment and improve deformation behavior due to the particles' stimulated nucleation effect (PSN) [46,51,[63][64][65]. During MDF, the Mg 2 Si phase was noticeably fragmentized, the result of both the temperature and strain effect.…”

“…The MDF was performed at 150, 250, and 350 • C. The true stress vs. true strain dependencies were corrected considering the increase in the strain rate during compression [51] (Figure 3). Relatively stable flow stage occurred in a strain interval of 0.1-0.4.…”

Microstructure and Phase Composition of Novel Crossover Al-Zn-Mg-Cu-Zr-Y(Er) Alloys with Equal Zn/Mg/Cu Ratio and Cr Addition

“…The nano-sized precipitates effectively pinned the dislocation motion and migration of the sub-grains and grain boundaries [28,36,41]. On the other hand, micronsized intermetallic particles serve as effective centers for nucleation of recrystallized grains, relying on the particle stimulated nucleation effect [41,[55][56][57][58][59][60]. These processes take place in the investigated alloys.…”

Crystallography and Applications of Metallic Materials

“…The following work also concerns with ultrafine-grained materials, specifically, an Al-Mg-Zr-Ni-based alloy. The influence of Ni addition (during multidirectional forging) on nucleation was analyzed Contribution (7). Therefore, it was concluded that nucleation and precipitate formation were favored by the addition of an element (Ni).…”