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•During annealing, the growth characteristics of Al-Er intermetallic compounds are accord with layer-terraced growth.•In Al-Er system, AlEr grows by consuming Er component, the growth ...of Al3Er proceeds by swallowing AlEr.•The pre-exponential factor and activation energy of the Al3Er are 7.126 × 10−8 m2·s−1 and (88.4 ± 5.3) kJ·mol−1 respectively.•Al-Er diffusion couples were successfully prepared by casting cladding in the atmosphere.
The diffusion growth of intermetallic compounds in Al-Er alloys are closely related to the properties of the alloys. The current work aims at explaining the dominance of Al3Er in the Al-Er alloys precipitation phases and the interface thin layer phenomenon by diffusion couple technique, estimating the parabolic growth constant and diffusion activation energy of intermetallic compound in Al-Er diffusion couples to provide theoretical guidance for the design of new Al-Er alloys. In this work, Al-Er diffusion couples were successfully prepared by casting-cladding method in the atmosphere. The growth of Al-Er intermetallic compounds at diffusion couple interface during annealing were observed and recorded by High-Temperature Laser-Scanning Confocal Microscopy at 673, 698, 723 and 748 K respectively. The results show that the growth characteristics of Al-Er intermetallic compounds were accord with layer-terraced growth during annealing. The thickness of intermetallic compound was linear with the square root of time at experimental temperature. The intermetallic compound layer was composed of Al3Er and a very thin AlEr phase. The parabolic growth constants of Al3Er phase at 673, 698, 723 and 748 K were 1.017 × 10−14, 1.609 × 10−14, 3.111 × 10−14 and 4.76 × 10−14 respectively. The activation energy of Al3Er phase was (88.4 ± 5.3) kJ/mol and the pre-exponential factor was 7.126 × 10−8 m2/s.
Double-layered manganites are natural superlattices with low thermal conductivity, which is of importance for potential thermoelectric applications. The Gd2−2xSr1+2xMn2O7 (x = 0.5; 0.625; 0.75) were ...prepared by the solid-state reaction method. All the samples crystallize in the tetragonal I4/mmm Sr3Ti2O7 type structure. The unit cell volume and the distortion in the MnO6 octahedra increase with increasing Gd content. Their thermoelectric properties were investigated between 300 and 1200 K. All exhibit an n-type semiconducting behavior. The electrical conductivity (σ) increases while the absolute value of the Seebeck coefficient (|S|) decreases with increasing Gd content. Simultaneous increases in σ and |S| with increasing temperature are observed at temperatures approximately higher than 600 K, and the power factor reaches a maximum value of 18.36 μW/(m K²) for x = 0.75 at 1200 K. The thermal conductivity (κ) is lower than 2 W/(m K) over the temperature range of 300–1000 K for all the samples and a maximum dimensionless figure of merit ZT of 0.01 is obtained for x = 0.75 at 1000 K.
Bi-based YbMg2Bi1.98 Zintl compounds represent promising thermoelectric materials. Precise composition and appropriate doping are of great importance for this complex semiconductor. Here, the ...influence of Zn substitution for Mg on the microstructure and thermoelectric properties of p-type YbMg1.85−xZnxBi1.98 (x = 0, 0.05, 0.08, 0.13, 0.23) was investigated. Polycrystalline samples were prepared using induction melting and densified with spark plasma sintering. X-ray diffraction confirmed that the major phase of the samples possesses the trigonal CaAl2Si2-type crystal structure, and SEM/EDS indicated the presence of minor secondary phases. The electrical conductivity increases and the lattice thermal conductivity decreases with more Zn doping in YbMg1.85−xZnxBi1.98, whereas the Seebeck coefficient has a large reduction. The band gap decreases with increasing Zn concentration and leads to bipolar conduction, resulting in an increase in the thermal conductivity at higher temperatures. Figure of merit ZT values of 0.51 and 0.49 were found for the samples with x = 0 and 0.05 at 773 K, respectively. The maximum amount of Zn doping is suggested to be less than x = 0.1.
High-temperature forming behaviors of a 7046-aluminum alloy were investigated by hot compression experiments. The microstructural evolution features with the changes in deformation parameters were ...dissected. Results indicated the formation of massive dislocation clusters/cells and subgrains through the intense DRV mechanism at low compression temperature. With an increase in deformation temperature, the annihilation of dislocations and the coarsening of subgrains/DRX grains became prominent, due to the collaborative effects of the DRV and DRX mechanisms. However, the growth of subgrains and DRX grains displayed the weakening trend at high strain rates. Moreover, two constitutive models involving a physically based (PB) model and a gate recurrent unit (GRU) model were proposed for predicting the hot compression features. By validation analysis, the predicted values of true stress perfectly fit with the experimental data, indicating that both the proposed PB model and the GRU model can accurately predict the hot compression behaviors of 7046-aluminum alloys.
Introduction This study examines the impact of digital new media art on the health literacy and digital health literacy of older adults. It explores how digital new media art influences the social ...adaptability of the older adult, with a focus on variations in their engagement with digital technologies and community activities. Methods The research employed interviews and observations of older adult participants from communities A and B . Data were collected on their smartphone usage, community engagement, and access to technological infrastructure. The study also assessed their interaction with digital new media across various domains, including interpersonal communication, information retrieval, entertainment, practical applications, and mobile payments. Results The study found significant differences in engagement with digital new media art among the older adult. Participants with prior computer experience were generally more skilled in using smartphones and more active in community events. In contrast, individuals in community B showed lower acceptance of digital new media art and no clear association with community participation. There was substantial variability in their use of digital media for information retrieval, entertainment, practical applications, and mobile payments. Some older adult individuals demonstrated proficiency with these technologies, while others were more reserved. Discussion The findings suggest that digital new media art can enhance community participation and social adaptability among older adults, particularly those with prior computer experience. However, disparities in digital media usage highlight the need for targeted interventions to improve digital health literacy and engagement across different community settings. The study underscores the importance of addressing these disparities to ensure that all older adults can benefit from digital advancements, thereby improving their overall well-being and health literacy.
Microstructure is a significant factor that influences the mechanical properties of alloys. The effect of multiaxial forging (MAF) and subsequent aging treatment on the precipitated phases of ...Al-Zn-Mg-Cu alloy remains unclear. Therefore, an Al-Zn-Mg-Cu alloy was processed by means of solid solution and aging treatment, and MAF and aging treatment in this work, and the composition and distribution of precipitated phases were characterized in detail. The MAF results for dislocation multiplication and grain refinement were found. The high density of dislocation greatly accelerates the nucleation and growth of precipitated phases. Thus, the GP-zones almost transform into precipitated phases during subsequent aging. The MAF and aging alloy has more precipitated phases than the solid solution and aging treated alloy. The precipitates on the grain boundary are coarse and discontinuously distributed due to dislocation and grain boundary promoting the nucleation, growth and coarsening of the precipitates. The hardness, strength, ductility and microstructures of the alloy have been studied. Without compromising the ductility much, the MAF and aging alloy has higher hardness and strength, with values of 202 HV and 606 MPa, respectively, and an appreciable ductility of 16.2%.
With the aim of obtaining a refining flux that is stable and provides effective refining of aluminum melt, a new strategy of designing the flux composition has been proposed. Ten fluxes were ...designed, by selecting ten molten salt compounds according to their thermophysical parameters, physical properties, and thermodynamic analysis. The melting points of the ten fluxes, and the phases transformation of the fluxes after melting, were studied by DSC and XRD, respectively. The contact angles between four groups of fluxes and alumina at refinement temperatures were studied, and the effect of refinement was characterized by a metallographic microscope. The process of the fluxes removing inclusions and degassing was analyzed thermodynamically. The research findings indicate that flux #10 (11.0 wt.%NaF, 29.5 wt.%NaCl, 46.5 wt.%Na
CO
, 3.0 wt.%CaF
, 10.0 wt.%Na
AlF
) has a melting point (562.2 °C) below the refining temperature. At the refining temperature (760 °C), flux #10 has the lowest contact angle, of 12.78°. In addition, compared to that of flux STJ-A3, currently used in practice, flux #10 has a better refining effectiveness, with the pores and inclusions content of the sample being reduced to 1.11% from 2.96%.
The mechanism of solid-state dendrite formation in high-aluminum Fe-Al alloys is not clear. Applying an in-situ observation technique, the real-time formation and growth of FeAl solid-state dendrites ...during the eutectoid decomposition of the high-temperature phase Fe
Al
is visualized. In-situ experiments by HT-CSLM reveal that proeutectoid FeAl usually does not preferentially nucleate at grain boundaries regardless of rapid or slow cooling conditions. The critical radii for generating morphological instability are 1.2 μm and 0.9 μm for slow and rapid cooling, respectively. The morphology after both slow and rapid cooling exhibits dendrites, while there are differences in the size and critical instability radius
, which are attributed to the different supersaturation
and the number of protrusions
The combination of crystallographic and thermodynamic analysis indicates that solid-state dendrites only exist on the hypoeutectoid side in high-aluminum Fe-Al alloys. A large number of lattice defects in the parent phase provides an additional driving force for nucleation, leading to coherent nucleation from the interior of the parent phase grains based on the orientation relationship {3¯30}
//{1¯10}
, <111¯>
//<111¯>
. The maximum release of misfit strain energy leads to the preferential growth of the primary arm of the nucleus along <111¯> {1¯10}. During the rapid cooling process, a large supersaturation is induced in the matrix, driving the Al atoms to undergo unstable uphill diffusion and causing variations in the concentration gradient as well as generating constitutional undercooling, ultimately leading to morphological instability and the growth of secondary arms.
An inhomogeneous microstructure induced by high rotating speed submerged friction stir processing (HRS-SFSP) on 6061 aluminum alloy was researched in detail.The microstructures of the aluminum alloy ...processing zone were characterized by electron backscattered diffraction (EBSD) and transmission electron microscope (TEM) qualitatively and quantitatively.The results show that the recrystallization proportion in the inhomogeneous structure of the processing zone is 14.3%, 37.8% and 35.9%, respectively. Different degrees of grain deformation can affect the dislocation and lead to the formation of a plastic-elastic interface. At the same time, the second-phase particles in the processing zone were inhomogeneity and relatively, which further promotes the plastic-elastic interface effect. The plastic-elastic interface can significantly improve the strength of aluminum alloy, whileat the same time, rely on recrystallized grains to provide enough plasticity. When the rotation speed was 3600 r/min, the strength and ductility of the aluminum alloy after HRS-SFSP were increased by 48.7% and 10.2% respectively compared with that of BM. In all, the plastic-elastic interface can be formed by using high rotating speed submerged friction stir processing, and the strength-ductility synergy of aluminum alloy can be realized at the plastic-elastic interface.
Hot tensile features of a commercial 7046 aluminum alloy are investigated through employing high-temperature tensile tests. The evolving mechanisms of microstructures over high-temperature tensile ...parameters are systematically revealed. A unified dislocation-density related constitutive model is proposed to reconstruct hot tensile stress–strain behaviors. Results imply that the microstructural evolving features are acutely influenced by tensile parameters. The principal softening mechanism converts from dynamic recovery (DRV) to dynamic recrystallization (DRX), as the tensile temperature reaches 350 °C or above. The combined DRX nucleation features containing discontinuous DRX (DDRX) as well as continuous DRX (CDRX) together emerge. Furthermore, the CDRX behavior characterized by substructural nucleation and interaction becomes apparent at low tensile temperature or high strain rate, while the DDRX process is weaken. Through validation, the reproduced tensile stress, grain size as well as DRX fraction are good accordance with experimented values, which proves the proposed dislocation-density related equation can enjoy an outstanding reproduced capacity for the thermal tensile features of a 7046 aluminum alloy.
