This study investigated the effect of welding current during gas metal arc welding (GMAW) on the microstructure and composition of an Al 5083 alloy. As the welding current increased from 650 to 950 A, several changes were observed in the heat-affected zone (HAZ): grain coarsening and the formation of liquation cracks, and in the weld zone (WZ): increasing average secondary arm spacing and Mg loss. Therefore, the welding currents above 800 A are likely to cause liquation cracks in the HAZ and deterioration of the alloy's mechanical properties. Thus, welding condition with low heat input must be applied to improve the mechanical properties of the welds. This study provides a correlation between the weldability of Al 5083 alloy and welding current, offering a competitive advantage of liquid hydrogen storage containers.
The microstructure and dilatation for 0.15C steels were investigated to define the phase transformation during the quenching and partitioning (Q&P) process. For the one step Q&P dilatation, the isothermal martensite/bainite transformation occurred because the holding temperature was between Ms and Mf. The isothermally transformed martensite/bainite and the athermally transformed martensite were produced by a loss of retained austenite. As the holding time increased, new martensite-start (Ms) temperature produced from the final quenching process decreased due to the carbon partitioning from the martensite to the retained austenite. This was the direct evidence of increment for the retained austenite stability. For the two step Q&P dilatation, the isothermal bainitic transformation occurred because the partitioning temperature was larger than the Ms and new Ms. The partitioning at 400°C indicated the short incubation period for the bainite transformation than the 350°C partitioning because the partitioning at 400°C should acquire the larger thermal driving force for carbon partitioning than the 350°C partitioning. A quick drop of Ms and short period of bainite incubation for the 400°C partitioning steel were also the direct evidence of significant effects of carbon partitioning on the stability of retained austenite. Key words: Retained austenite, Partitioning, Isothermal martensite transformation, Bainite transformation, Carbon diffusion
This study investigates the fracture behavior during hole expansion testing of a 980 MPa hot‐rolled Fe–Cr–Ti–B steel, with particular focus on analyzing the microvoid initiation and crack propagation during plastic deformation. The microstructure of the steel consists of a tempered martensite matrix and granular bainite, with each constituent phase being identified by field emission scanning electron microscopy, transmission electron microscopy, micro Vickers hardness, and nanoindentation. Microvoids are observed at the intergranular boundaries, transgranular regions, and at the interface of precipitates/matrix and non‐metallic inclusions/matrix. The main crack is generated at the intergranular interface between the tempered martensite and granular bainite, an area exhibiting a large deviation in hardness and elastic modulus. The tempered martensite has a greater hardness of 385 Hv and elastic modulus of 287 GPa, as opposed to the 326 Hv and 257 GPa of the granular bainite. Due to this difference in elastic modulus, the granular bainite plastically deforms at a lower applied stress than the tempered martensite. The main crack obtained from the hole expansion test generates a fractography mixed with dimple and quasi‐cleavage fracture pattern. Therefore, the crack initiated at the interface of the tempered martensite and granular bainite is propagated along the transgranular regions.
In atomically thin semiconductors, localized exciton (X$_L$) coupled to light shows single quantum emitting behaviors through radiative relaxation processes providing a new class of optical sources for potential applications in quantum communication. In most studies, however, X$_L$ photoluminescence (PL) from crystal defects has mainly been observed in cryogenic conditions because of their sub-wavelength emission region and low quantum yield at room temperature. Furthermore, engineering the radiative relaxation properties, e.g., emission region, intensity, and energy, remained challenging. Here, we present a plasmonic antenna with a triple-sharp-tips geometry to induce and control the X$_L$ emission of a WSe$_2$ monolayer (ML) at room temperature. By placing a ML crystal on the two sharp Au tips in a bowtie antenna fabricated through cascade domino lithography with a radius of curvature of <1 nm, we effectively induce tensile strain in the nanoscale region to create robust X$_L$ states. An Au tip with tip-enhanced photoluminescence (TEPL) spectroscopy is then added to the strained region to probe and control the X$_L$ emission. With TEPL enhancement of X$_L$ as high as ~10$^6$ in the triple-sharp-tips device, experimental results demonstrate the controllable X$_L$ emission in <30 nm area with a PL energy shift up to 40 meV, resolved by tip-enhanced PL and Raman imaging with <15 nm spatial resolution. Our approach provides a systematic way to control localized quantum light in 2D semiconductors offering new strategies for active quantum nano-optical devices.
The incidence of mammary gland tumors in dogs is a significant issue, characterized by notable rates of malignancy, recurrence, and disease burden. However, the lack of comprehensive information and correlated studies has presented challenges in establishing an effective surgical treatment strategy. In this study, a cohort of 95 dogs diagnosed with mammary tumors underwent evaluation using various surgical methods, medications, ovariohysterectomy, and assessments of margin completeness to analyze clinical outcomes. Significant clinical outcomes were observed following radical mastectomy and conservative surgeries, irrespective of TNM stages and histopathological grade of malignancy. Complete excision demonstrated significantly improved survival time and disease-free interval compared to incomplete excision. It is noted that complete surgical excision provides benefits, even in cases where lymphatic invasion is present. However, further investigations are necessary to validate the clinical results and mitigate side effects from radical mastectomy. Despite postoperative complications, several studies continue to advocate for more radical mastectomies due to their favorable risk-benefit ratio. Moreover, advanced inpatient treatments can now effectively manage or mitigate many of these complications. This study emphasizes the critical role of surgical proficiency and postoperative medication in treating malignant mammary tumors in dogs, and it provides insights that may contribute to the development of more effective treatment strategies for this condition.
Atomically Thin Semiconductors In article number 2102893, Junsuk Rho, Kyoung-Duck Park, and co-workers develop a triple-sharp-tips nano-antenna to facilitate radiative emissions of the localized states in 2D semiconductors. The localized exciton is deterministically induced and probed at room temperature through this novel concept of tip-enhanced cavity-spectroscopy. This new approach provides a practical way to control single-photon generation at room temperature, which is the centerpiece of quantum optical communications.
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