Search

Abstract The present work revealed a potential to control the static recrystallization kinetics through regulating the feature of pre-existing Mg 17 Al 12 particles in Mg-Al-Zn alloys. The AZ31 (Mg-3Al-1Zn) with rarely dispersoids exhibits the fastest recrystallization rate, while the AZ61 (Mg-6Al-1Zn) with only fine particles (∼100 nm) recrystallizes slower than AZ91 (Mg-9Al-1Zn) containing Mg 17 Al 12 precipitates with scattered size distribution (ranging from less than 100 nm to above 0.6 μm). Especially, we found that coarse Mg 17 Al 12 particles in AZ91 are easier to trigger particle stimulated nucleation (PSN) at 275 °C than 175 °C, which compensates the strong recrystallization inhibition of fine dispersoids, leading to the recrystallization dramatically transforms from retarded to accelerated. Graphical abstract Image 1 Highlights • The precipitate feature notably affects the kinetics of static recrystallization. • Recrystallization of alloys with mixed particle size is sensitive to temperature. • Coarse particles in Mg-9Al-1Zn accelerate recrystallization at high temperature. • The study shows an efficient route to control the static recrystallization process. [ABSTRACT FROM AUTHOR]

• Al matrix composites reinforced with different nanoparticles were investigated. • The corrosion behaviors of the composites were related to the passive film. • TiC p were beneficial for improving the corrosion behavior, but TiB 2p were not. • TiC p reduced the grain boundary phases, improving the corrosion behavior. • TiB 2p at grain boundaries form more corrosion channels, increasing the corrosion rate. Nanosized TiC and TiB 2 particles (TiC p , TiB 2p) can increase the mechanical properties of Al alloys. However, their effects on the corrosion performance of Al alloys are relatively less understood. The corrosion behavior of Al-Mg-Si alloys is improved by adding TiC p and worsened by adding TiB 2p. These changes result from i. TiC p refining the grain structure by acting as nucleants and reducing the number of grain boundary phases and ii. TiB 2p segregating at grain boundaries and accelerating the corrosion. This provides a selection criterion that can be utilized for reinforcement nanoparticles for wrought Al alloys that are applied in corrosive environments. [ABSTRACT FROM AUTHOR]

Al Cu alloys inoculated by in-situ nano-sized particles crystallized from Ni-Nb-Ti amorphous alloys were prepared by casting method in this work. Different compositions of Ni-Nb-Ti amorphous alloys significantly enhanced heterogeneous nucleation for α-Al and promoted obvious grain refinement of the Al Cu alloys. It was found that 0.05 wt% Ni-Nb-Ti amorphous alloys addition caused a significant and efficient refinement on α-Al (from 200 μm to 39 μm) and θ′ phase (from 146.4 nm to 37.6 nm). The strength and ductility of the inoculated alloy were improved significantly at high temperature. The tensile strength and fracture strain of the alloy inoculated by 0.05 wt% Ni-Nb-Ti amorphous alloy for 20 min at 533 K under the strain rates of 10−1 s−1 were increased by 32.63% and 90.35% respectively, compared to those of the uninoculated alloy. The nano-sized NiTi particles contributed to the grain refinement of α-Al, and grain refinement shortened the solute atomic diffusion distance and refined θ′ phase during heat treatment, resulting in higher strength and plasticity at high temperature. The model developed for this new type Al Cu alloy is found to be efficient in predicting the stress at 453 K–533 K under the strain rates of 10−4 s−1 to 10−1 s−1. • In-situ nano-sized NiTi can serve as efficient heterogeneous nuclei of α-Al. • Inoculation caused a significant refinement on α-Al and precipitation θ′ phase. • The tensile strength and fracture strain were increased by 32.63% and 90.35% respectively at 533 K with 10−1 s−1. • The enhanced tensile property was due to the finer θ′ phase which impeded dislocation motion. • A stress prediction model was presented at 453 K–533 K under the strain rates of 10−4 s−1 to 10−1 s−1. [ABSTRACT FROM AUTHOR]