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Advancements in remote sensing technology have enabled the acquisition of high spatial and radiometric resolution imagery, offering abundant and reliable data sources for forest fire monitoring. In order to explore the ability of Sustainable Development Science Satellite 1 (SDGSAT-1) in wildfire monitoring, a systematic and comprehensive study was proposed on smoke detection during the wildfire early warning phase, fire point identification during the fire occurrence, and burned area delineation after the wildfire. The smoke detection effect of SDGSAT-1 was analyzed by machine learning and the discriminating potential of SDGSAT-1 burned area was discussed by Mid-Infrared Burn Index (MIRBI) and Normalized Burn Ratio 2 (NBR2). In addition, compared with Sentinel-2, the fixed-threshold method and the two-channel fixed-threshold plus contextual approach are further used to demonstrate the performance of SDGSAT-1 in fire point identification. The results show that the average accuracy of SDGSAT-1 fire burned area recognition is 90.21%, and a clear fire boundary can be obtained. The average smoke detection precision is 81.72%, while the fire point accuracy is 97.40%, and the minimum identified fire area is 0.0009 km2, which implies SDGSAT-1 offers significant advantages in the early detection and identification of small-scale fires, which is significant in fire emergency and disposal. The performance of fire point detection is superior to that of Sentinel-2 and Landsat 8. SDGSAT-1 demonstrates great potential in monitoring the entire process of wildfire occurrence, development, and evolution. With its higher-resolution satellite imagery, it has become an important data source for monitoring in the field of remote sensing.

The synthesis and characterization of MgO-ZrO2 heterostructures are examined in this work. To promote the creation of nanowires, the Si substrate is first covered with a catalyst layer of various Au thicknesses. Sputtering is used to achieve this deposition. After that, chemical vapor deposition (CVD) with a Au catalyst layer is used to create MgO nanowire arrays on the silicon substrate. Second, MgO/ZrO2 Core–shell Nanowire Arrays are created by applying ZrO2 layers to the surface of MgO nanowires of different diameters using chemical vapor deposition (CVD) procedures. The presence of both magnesium oxide (MgO) and zirconium dioxide (ZrO2) in their oxidized forms was shown by the detailed characterization of the MgO-ZrO2 core–shell nanowire samples utilizing a variety of methods. Phase formation, mechanical homogeneity, optical characteristics, and topographical structure and roughness were all thoroughly examined at various stresses. MgO hardness values ranged from 1.4 to 3.2 GPa, whereas MgO-ZrO2 ranged from 0.38 to 1.2 GPa. The I–V parameter study was a further step in the examination of the heterostructure’s electrical properties. The structural, morphological, optical, mechanical, and electrical properties of the MgO-ZrO2 heterostructure were all thoroughly described using these techniques.

Using surface mechanical attrition treatment (SMAT), a gradient structure composed of two gradient structure (GS) layers and a coarse grain (CG) layer was generated from a Cu-5.7 wt pct Ge alloy, significantly improving the yield strength of the sample. Unloading–reloading tests showed an unusual Bauschinger effect in these GS samples. The back stresses caused by the accumulated geometrically necessary dislocations (GNDs) on the GS/CG border increased with increasing strain. As found by electron backscatter diffraction (EBSD), the GNDs are mainly distributed in the gradient structured layer, and the density of the GNDs increase with increasing SMAT time. The effect of the back stress increased with increasing SMAT processing time due to the increase in the strain gradient. The pronounced Bauschinger effect in a GS sample can improve the resistance to forward plastic flow and finally contributes to the high strength of GS samples.

Heterostructured materials consist of heterogeneous zones with dramatic variations in mechanical properties, and have attracted extensive attention due to their superior performance. Various heterostructured materials have been widely investigated in recent years. In the present study, a combination of two different types of heterogeneous structures, a surface bimodal structure and gradient structure, was designed using the traditional surface mechanical attrition treatment (SMAT) method in pure copper, and the mechanical properties and microstructural evolution of dual-heterostructure Cu were studied in depth. In total, 100 stainless steel balls with a diameter of 6 mm were utilized to impact the specimen surface at room temperature for a short period of time. In this work, the sample surface was divided into hard areas and soft areas, along with a roughly 90 μm gradient structure in the cross-sectional direction after 30 s of SMAT processing. After the partial SMAT processing, lasting 30 s, the strength increased to 158.0 MPa and a considerable ductility of 25.7% was sustained, which overcomes the strength–ductility trade-off. The loading–unloading–reloading (LUR) test was utilized to measure the HDI stress, and the result showed that the HDI stress of the partial SMAT sample was much higher than the annealed one, especially for the Cu-SMAT-30S specimen, the strength of which increased from 80.4 MPa to 153.8 MPa during the tensile test. An in situ digital image correlation (DIC) investigation demonstrated that the strain developed stably in the Cu-SMAT-10S specimen. Furthermore, electron backscatter diffraction (EBSD) was carried out to study the microstructural evolution after partial SMAT processing; the KAM value increased to 0.34 for the Cu-SMAT-10S specimen. This research provides insights for the effective combination of superior strength and good ductility in dual-heterostructure materials.

Alloys with a gradient structure (GS) exhibit a superior combination of strength and ductility. However, the effects of treatment temperature and stacking fault energy on the tensile behavior and microstructure evolution of GS alloys have not been systematically investigated. In this study, GS Cu-Al-Zn alloys with different stacking fault energy (SFE, 40/7 mJ/m2) were prepared using surface mechanical attrition treatment (SMAT) at cryogenic and room temperature, respectively. The microstructure results indicate that more stacking faults and deformation twins were activated in the SFE-7 alloys at cryogenic temperature, which led to higher strength compared to that of the alloys SMAT-ed at room temperature. In addition, it was found that the yield strength and hetero-deformation-induced (HDI) stress of the SFE-7 alloy were significantly higher than those of the SFE-40 alloy, resulting in a good combination of strength and ductility. Furthermore, more dispersed strain bands were observed in the SFE-7 sample during whole tensile deformation, which contributes to higher ductility.

SAF2507 duplex stainless steel (DSS) is often used as a structural component in ocean-going vessels and marine petroleum exploitation equipment, which require superior mechanical properties. In this study, we used cold rolling (CR) at room temperature with 55% or 80% deformation amounts and subsequent annealing at 1273 K in 1 min to prepare SAF2507 samples with a heterogeneous structure (HS) that was composed of ferrite and austenite phases with different grain sizes. Compared with the homogeneous structure samples, the yield strength of the HS samples increased, while the ductility did not decrease. The 55%-1273 and 80%-1273 samples exhibited the hetero-zone boundary-affected regions on both sides of the grain boundary, phase boundary, and twin boundary. This resulted in hetero-deformation-induced (HDI) strengthening and strain hardening of samples during tensile deformation, which improved the ultimate tensile strength of the HS samples while maintaining a good uniform elongation. In addition, the heterogeneous structure of DSS had better corrosion resistance than the initial sample of coarse grain (CG) structure; mainly because the HS samples had finer grains and more grain boundaries on the DSS surface than the CG structure, which is conducive to the formation of high-density passivation film on the surface of stainless steel. The current study provides a new method of material selection of some structural components with the demands of high strength and good ductility.

In this study, two different types of heterogeneous structures were prepared by controlling different surface mechanical attrition treatment (SMAT) time (5 s, 10 s, 30 s, 60 s). The effect of heterogeneous Cu with bimodal grain size structure (BGSS) and gradient structure (GS) on heterogeneous deformation induced (HDI) stress and mechanical properties was investigated systematically. By combining surface morphology with microhardness distribution, it was found that the surface grains of the SMAT-ed Cu (5 s and 10 s) were partially refined to exhibit BGSS, while the surface grains of SMAT-ed Cu (30 s and 60 s) were sufficiently refined to form GS. The load-unload-reload (LUR) tests results showed that HDI stress for SMAT 60s Cu was much higher than that of the SMAT 10s Cu. Furthermore, microstructure characterizations revealed that SMAT-ed Cu with BGSS and GS suppressed strain localization, which resulted in high strength and reasonable ductility.

Annealing of deformed metals is considered as a process which necessarily leads to softening, due to the annihilation of lattice defects. However, in laminated materials, annealing at moderate temperatures may induce hardening. In this study, a laminated structure at two sides of the sample is produced by ultrasonic introduced intermittently for 15 min, during the electrodeposition process. For comparison, a sandwich structure is prepared under ultrasonic without interruption at two sides of the sample. All the samples are annealed for 30 min at 373 K, 473 K and 573 K. The common softening after annealing is observed for the sample without laminated structure in the two sides. However, for the other sample that possesses laminated structure in the same area at the two sides, the strength and ductility increase rather than decrease after annealing. The sample that possesses laminated structure in the same area at the two sides annealed at 373 K shows an evident change, which increases in σ 0.2 from 299 to 353 MPa, in σ UTS from 477 to 533 MPa, and in ε ue from 7.6% to 9.5%. According to the XRD results, annealing-induced hardening is not attributable to occurring phase transformation. Detailed microstructural TEM results demonstrate that the annealing-induced hardening is attributed to the surface laminated interfaces and high-density growth twins in interfacial transition zones. In addition, the detwinning occurred during subsequent tensile deformation, also plays a crucial role.

The purpose of this paper is to investigate the effect of dynamic recovery on the mechanical properties of copper (Cu) during surface mechanical attrition treatment (SMAT) at both room temperature (RT) and cryogenic temperature (CT). Copper sheets were processed by SMAT at RT and at CT for 5, 15, and 30 min, respectively. The Cu samples after SMAT at RT for 30 min exhibited better ductility but lower strength than the samples after SMAT at CT for 30 min due to dynamic recovery. X-ray diffraction analysis indicated that decreasing temperature during SMAT led to an increase in the twin and dislocation densities. In addition, a thicker gradient structure layer with finer grains was obtained in the SMAT-processed Cu samples at CT than at RT. The results indicated that SMAT at CT can effectively suppress the occurring of dynamic recovery and produce ultrahigh strength pure copper without seriously sacrificing its ductility.

In the present work, Cu–Al alloys were processed by surface mechanical attrition treatment (SMAT) under both room and liquid nitrogen temperature (LNT) conditions. In contrast to room temperature (RT) SMAT, dynamic recovery and recrystallization were largely suppressed during the LNT process. A gradient microstructure was obtained due to the gradient strain and strain rate impacted onto the sample. Microhardness measurement showed that the hardness values gradually decreased from the top surface to the central region. The local hardness of the top surface layer of the LNT and RT SMAT Cu–4.5% Al samples reached maximum values of 1.52 and 1.28 GPa, respectively. The Cu–4.5% Al alloy exhibited an improved yield strength of ∼496 MPa and a higher ductility (compared with literature data of Cu–Al alloys synthesized traditional severe plastic deformation methods) of 15.4% after the LNT SMAT process. A brittle-ductile failure pattern was easily distinguished after fracture. Moreover, the LNT SMAT is a low-cost process with high productivity and can be applied to various types of metallic production.