The cold angular rolling process (CARP) is being developed as a continuous severe plastic deformation technique, which can process metal sheets without any length limitations at room temperature. CARP contains cold rolling and equal‐channel angular process components. The sheet thickness is kept consistent before and after CARP, allowing multiple passes of the sheet. The desired microstructure and mechanical properties can be achieved in the processed metallic sheets. The current study is aimed to evaluate the capability of CARP by processing copper sheets with different sheet widths for repetitive passes. The CARP‐treated sheets are examined by lab‐scale X‐ray and high‐energy synchrotron X‐ray diffraction to investigate the evolution in dislocation density, texture, and strain anisotropy, and by tensile testing to identify the bulk mechanical properties. The digital image correlation method is applied to tensile testing so that strain localization within the sample gauge is visualized and deformation behavior is evaluated after yielding till postnecking by estimating the hardening exponent and strain hardening rate of the CARP‐treated sheet. Comparing the reported continuous and multiple‐step processes on Cu and its alloys, the present study confirms that the CARP is potentially a useful sheet process for strengthening ductile metals.

Al-Mg alloy disks were produced from Mg sandwiched between Al through 100 turns of high-pressure torsion (HPT) at 6.0 GPa at room temperature, resulting in high microhardness of Hv 300–350 in regions experiencing a nominal shear strain > 390. While compositional mapping using scanning electron microscopy energy-dispersive spectroscopy (EDS) showed a uniform distribution of Mg through the disk thickness at 1.5 mm and 3.0 mm from the disk center, transmission electron microscopy EDS showed a heterogeneous distribution of Mg remained on the nanoscale. Although HPT induces enough mixing to result in face-center-cubic Al with supersaturations of Mg of up to 20 at.

Solid-state welding of Al 1043 sheets is achieved via high-pressure torsion (HPT) processing to produce bulk nanostructured Al disks. A homogeneous nanostructure without segregation is observed, with grain sizes of approximate to 430-470 nm. Miniature tensile testing, coupled with the digital image correlation (DIC) technique, is employed to determine the room-temperature tensile deformation behavior, particularly the nonuniform behavior with necking, of the HPT-bonded ultrafine-grained (UFG) aluminum, comparing it with annealed coarse-grained counterpart. The HPT-bonded UFG Al exhibits a large fraction of post-necking strain, which is supported by the estimated high strain rate sensitivity value of m = 0.085, suggesting the delay of local necking leading to tensile fracture. Detailed DIC analysis reveals prolonged diffuse necking, thus delaying local necking, in the HPT-bonded UFG Al, while the annealed samples show high fractions of local necking during the nonuniform deformation. Moreover, the DIC data illustrate that local necking predominantly occurred at a limited neck zone, maintaining a plateau strain distribution at the out-of-neck zone throughout necking deformation toward tensile failure for both annealed and UFG aluminum. The DIC method offers an alternative means to demonstrate the transition in necking behaviors of materials by estimating the plastic lateral contraction exponent. This report demonstrates miniature tensile testing coupled with DIC analysis of solid-state welded bulk nanostructured Al alloy through HPT. This study fully utilizes DIC-generated strain data to quantitatively determine the flow and necking behaviors of nanostructured materials, aiming to enhance comprehensive understanding and explore further opportunities to determine the superior ductility of UFG metals.image (c) 2024 WILEY-VCH GmbH

The auto industry makes extensive use of Al–Mg–Si alloys. This study investigated the effect of pre-cryorolling and room-temperature pre-rolling on the natural aging and bake hardening response of Al–0.92Mg–0.48Si alloy. The mechanical properties were analyzed using microhardness, tensile, and Erichsen cupping test. Optical microscope, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry were used to examine the microstructure of samples. The molecular dynamics simulation was also employed to study the dislocation evolution in samples deformed at room and cryogenic temperature. The results show that both room-temperature pre-rolling and pre-cryorolling introduced immediately after solid solution treatment can effectively inhibit the adverse effects of natural aging, and promote the precipitation of strengthening phase during paint baking, leading to an improved bake hardening response. Compared with the room-temperature pre-rolling, pre-cryorolling can further improve the bake hardening response because of higher dislocation density. The results of this study indicate that pre-cryorolling with a reduction of 15 pct is the most appropriate pre-deformation procedure for this alloy, both in terms of formability and bake hardening response.

High-entropy alloy particles (HEAPs) can markedly enhance the mechanical properties of metal matrix composites (MMCs). In this study, AA5083/Al0.5CoCrFeNi HEAPs MMCs with different HEAPs contents (0, 1, and 3 wt%) were prepared via a stir-casting, and then these MMCs sheets were hot rolled (573 K) and cryorolled (77 K), respectively. The mechanical properties of the MMCs sheets were measured by tensile testing and microhardness test. Additionally, their microstructures were analyzed by scanning electron microscopy and transmission electron microscopy. Results revealed that the ultimate tensile strength (UTS) of the as-cast AA5083/Al0.5CoCrFeNi HEAPs MMCs were improved from 203 to 257 MPa by adding 3 wt% HEAPs. And the mechanical properties of the MMCs sheets were improved after cryorolling. After cryorolling with 50% rolling reduction ratio, the MMCs with 1 wt% HEAPs had an UTS of 382 MPa, which was 1.9 times that of the MMCs before rolling. Finally, the strengthening mechanisms of HEAPs and cryorolling on the AA5083/HEAPs MMCs were discussed.

To explore the effect of cryorolling on the high-temperature mechanical properties of aluminium alloys, AA5083 sheets were rolled at 83, 173, and 298 K, and the rolled sheets were then subjected to high-temperature tensile testing at 748 K. The elongation to failure of the 83 K cryorolled samples reached 150% at a strain rate of 1 x 10(-3) s(-1), which was higher than those of the 173 K cryorolled samples (92%) and 298 K rolled samples (80%). Under this condition, the strain rate sensitivity coefficient of the 83 K rolled samples was 0.36, which reached the standard of superplasticity. The enhancement of plasticity of the 83 K cryorolled samples was attributed to the finer grains, the smaller second phase, and the subgrains alleviating more stress concentration. The main deformation mechanisms during the high-temperature tensile deformation were grain-boundary sliding and dislocation slip. Compared to the 298 K rolled sample, the grain size of the 83 K cryorolled sample was smaller, which was suitable for the grain-boundary sliding mechanism. In addition, the uniform distribution of high density dislocations prevented the dislocation slip mechanism but reduced the stress concentration and the nucleation and growth of cavities at high-temperature deformation.

The mechanical properties and microstructure of Al-Cu-Li alloy sheets subjected to cryorolling (−100 °C, −190 °C) or hot rolling (400 °C) and subsequent aging at 160 °C for different times were investigated. The dynamic precipitation and dislocation characterizations were examined via transmission electron microscopy and X-ray diffraction. The grain morphologies and the fracture-surface morphologies were studied via optical microscopy and scanning electron microscopy. Samples subjected to cryorolling followed by aging exhibited relatively high dislocation densities and a large number of precipitates compared with hot-rolled samples. The samples cryorolled at −190 °C and then aged for 15 h presented the highest ultimate tensile strength (586 MPa), while the alloy processed via hot rolling followed by 10 h aging exhibited the highest uniform elongation rate (11.5%). The size of precipitates increased with the aging time, which has significant effects on the interaction mechanism between dislocations and precipitates. Bowing is the main interaction method between the deformation-induced dislocations and coarsened precipitates during tensile tests, leading to the decline of the mechanical properties of the alloy during overaging. These interesting findings can provide significant insights into the development of materials possessing both excellent strength and high ductility.

We prepared AA6061 sheets by room-temperature rolling and low-temperature aging. We tested the tensile mechanical properties of the sheets at room temperature and cryogenic (173 K) temperature. The maximum difference between the cryogenic ultimate tensile strength and room-temperature ultimate tensile strength was 50 MPa for the sheets subjected to a rolling reduction ratio of 50% and aging at 393 K for 10 h. As the rolling reduction ratio increased, the lattice friction stress, dislocation strengthening, and precipitation strengthening of the material gradually approached a limiting value, thus reducing the difference between the strengths of the samples tensile tested at room temperature and cryogenic temperature. (C) 2020 Elsevier B.V. All rights reserved.

Patient with type 2 diabetes mellitus are at consistent risk of oral candidiasis, dental caries and dysfunction. Candiadisis is caused by different species such as Candida albicans, C. tropicalis, C. glabrata, C. dubliniensis. Nevertheless, C. albicans is the most frequent causative agent for candidiasis in human. Present work was undertaken to investigate Candida albicans infection among type 2 diabetic mellitus patients in Mahendranagar, Kanchanpur. Methods: A total of 103 oral samples were collected cross-sectionalfrom the patients at Mahakali zonal hospital from July 2015 to February 2016 and cultured in Potato Dextrose Agar to isolate the fungus. The fungus was characterized by colonial characteristics, gram staining and germ tube test. Results: Prevalence of C. albicans was found to be 70.8% among the patients of type 2 diabetic mellitus with 45 males and 28 females. The male patients are at high risk of infection, probably due to hard physical work as compared to female. Among the patients having high fasting blood glucose level 100-139 mg/dl were the most susceptible for infection. Similarly, C. albicans infection was highly prevalent among type 2 diabetes mellitus patients with high frequency among smoking and alcohol habits. Conclusion: Patients must play an important role in minimizing the yeast infection by regular checkup, dental care, and consultation better control of blood sugar and also to educate others about the common ailment that can adversely affect if not controlled earlier. Keywords: Diabetes, Candida albicans, Fungus, Infection, zonal hospital. Cite this Article Laxman Bhatt, Tek Raj Awasthi, Lok Raj Bhatt. Prevalence of Oral Candidiasis by Candida albicans in Patients with Type 2 Diabetes Mellitus Visiting Mahakali Zonal Hospital. Research & Reviews: A Journal of Microbiology & Virology. 2020; 10(1): 1–9p.

An Al-3.6Cu-1Li alloy was subjected to room temperature rolling and cryorolling to investigate their effects on microstructure evolution and mechanical properties. The microstructure and aging characteristics of the room temperature-rolled and the cryorolled alloys with 70% and 90% of thickness reductions were studied by microstructure analysis and mechanical tests. The samples subjected to cryorolling with 90% of thickness reduction have high strength and good toughness. This is mainly due to the inhibition of dynamic recovery and the accumulation of high-density dislocations in cryorolled samples. In addition, the artificial aging reveals that the temperature at which peak hardness is attained is inversely proportional to the deformation amount and directly proportional to the rolling temperature. Moreover, bright field images of cryorolled samples after aging indicate the existence of T1 (Al2CuLi) precipitates. This suggests that the high stored strain energy enhances the aging kinetics of the alloy, which further promotes the nucleation of T1 phases.

Aluminum alloys can be used in the fabrication of intricate geometry and curved parts for a wide range of uses in aerospace and automotive sectors, where high stiffness and low weight are necessitated. This paper outlines a review of various research investigations on the superplastic behavior of aluminum alloys that have taken place mainly over the past two decades. The influencing factors on aluminum alloys superplasticity, such as initial grain size, deformation temperature, strain rate, microstructure refinement techniques, and addition of trace elements in aluminum alloys, are analyzed here. Since grain boundary sliding is one of the dominant features of aluminum alloys superplasticity, its deformation mechanism and the corresponding value of activation energy are included as a part of discussion. Dislocation motion, diffusion in grains, and near-grain boundary regions being major features of superplasticity, are discussed as important issues. Moreover, the paper also discusses the corresponding values of grain size exponent, stress exponent, solute drag creep and power law creep. Constitutive equations, which are essential for commercial applications and play a vital role in predicting and analyzing the superplastic behavior, are also reviewed here.

CoCrNi equiatomic medium entropy alloy sheets were prepared by asymmetric rolling, cryorolling, and asymmetric cryorolling. The asymmetric cryorolled samples exhibited a noteworthy ultra-fine-grain heterogeneous lamella structure. The microstructure and corresponding hardness obtained by different rolling processes and subsequent annealing are compared. It can be seen from the results that the cryogenic deformation temperature had a stronger effect on the mechanical properties of the medium entropy alloys (MEA), compared with the shear strain caused by the asymmetric cryorolling. The effect of annealing temperature on texture components and volume fractions of the specially rolled samples was also analyzed. The result revealed that the recrystallized MEA exhibited similar texture components and the corresponding volume fraction, which indicated that the rolling process had limited influence on the formation of annealing texture. The recrystallized texture after annealing retained the deformation texture and twin related orientations appeared. Asymmetric rolled MEA showed strong random composition than symmetric rolled MEA regardless of rolling temperature. The recrystallized textures of the species obtained by the three rolling processes did not exhibit a significant dependence on the annealing temperature.

CrCoNi medium entropy alloy sheets were fabricated by asymmetric cryorolling (ACR) with rolling speed ratios of 1.2 (ACR1.2) and 1.6 (ACR1.6), followed by annealing at 873 K, 973 K, and 1073 K for 0.5 h. The mechanical properties were tested by a tensile test, and the microstructures were examined by transmission electron microscopy (TEM), scanning electron microscopy, and X-ray diffraction. Results show that the tensile strength of the ACR1.6-processed sheet reached 1340 MPa. This ternary alloy exhibits high strength and plasticity with a concomitant improvement in fracture toughness after annealing at 873 K, 973 K, and 1073 K. In addition, ACR1.6-processed sheets displayed better mechanical properties than ACR1.2-processed sheets. TEM results show that the grain refinement and the formation of a large fraction of deformation twins contributed to the enhanced mechanical properties of the CrCoNi medium entropy alloy.