Properties of High-Entropy Fe30Co20Ni20Mn20Al10 Alloy Produced by High-Energy Ball Milling

A high-entropy Fe30Co20Ni20Mn20Al10 (at%) alloy with a face-centered cubic (FCC) crystalline phase was produced through mechanical alloying. This study examined the development of its phases, microstructure, morphology, and magnetic characteristics. Scanning electron microscopy (SEM) was applied to assess the sample morphology in relation to milling times. The changes that the material underwent during milling were investigated using X-ray diffraction. The milling time affected the phase transformation. A single FCC solid solution (crystallite size = 12 nm) was found after 50 h of milling. Additionally, the magnetic characteristics were examined and shown to be associated with microstructural changes. The powder mixture exhibited behavior consistent with soft magnetics, with an Hc value of 8 Am-1 and an Ms value of 165 emu/g. The excellent soft magnetic characteristic may be related to the stability of the FCC phase, which was generated following a 30 h milling process. In addition, the low value of Ms may have originated from the presence of Al atoms in the solid solution and the development of large densities of interfaces and crystal defects.

Study of Structural, Compression, and Soft Magnetic Properties of Fe65Ni28Mn7 Alloy Prepared by Arc Melting, Mechanical Alloying, and Spark Plasma Sintering

Soft magnetic Fe65Ni28Mn7 (at. %) alloy was successfully synthesized by mechanical alloying and spark plasma sintering (SPS) and, in parallel, the same composition was prepared by arc melting (AM) for comparison. Several SPS conditions were tested. X-ray diffraction and scanning electron microscopy were used to investigate the structure, phase composition, and morphology of the samples. It was found that mechanical alloying produced BCC and FCC supersaturated solid solution after 130 h of milling, with a fine microstructure (i.e., crystallite size of 10 nm). Spark plasma sintering performed at 750 °C and 1000 °C under two pressures of 50 MPa and 75 MPa revealed stable FCC phases. A single FCC phase was observed after the arc melting synthesis. The magnetic properties of milled powders and solids obtained by AM and SPS were investigated. The specimen consolidated by SPS at 1000 °C under the pressure of 50 MPa exhibits soft magnetic behavior (coercivity 0.07 Oe), whereas the mechanically alloyed sample revealed hard magnetic behavior. The specimen consolidated at 750 °C under a pressure of 75 MPa showed a higher compressive strength of 1700 MPa and a Vickers hardness of 425 ± 18 HV. As a result, sintering at 750 °C/75 MPa can be utilized to enhance the mechanical properties, while those sintered at 1000 °C/50 MPa increase magnetic softness.

Study of Modified Magnesium Phosphate Cement for Fluoride Removal

In this study, we used a novel composite material based on magnesium phosphate cement (MPC) to explore the retention of fluoride from used water. Dead-burned magnesium oxide (MgO), ammonium dihydrogen phosphate (NH4H2PO4), and a few retarders were used to create this particular substance. Several studies have corroborated the performance of using aluminum in the capture of fluoride. From this perspective, we attempted to reinforce our matrix with different quantities of aluminum, which increased the resistance of the composite in water. The optimal conditions that were obtained were evaluated and scrutinized using a range of techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transforms infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET). The adsorbents demonstrated a powerful ability to remove fluoride from contaminated water and the defluoridation capacity was evaluated at 4.84 mg/g. Equilibrium modeling was carried out, and the experimental data were expressed in accordance with the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms.

Synthesis and Characterization of New Composite Materials Based on Magnesium Phosphate Cement for Fluoride Retention

In this research work, new composite materials based on magnesium phosphate cement (MPC) were developed to evaluate the retention of fluorine from wastewater. This material was prepared with dead burned magnesia oxide (MgO), ammonium dihydrogen phosphate (NH₄H₂PO₄), and some retarding agents. We chose to synthesize with hydrogen peroxide instead of water; alumina and zeolite were also added to the cement. The obtained optimal conditions were studied and analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), BET, and thermogravimetric analysis (TGA). The adsorbents showed a strong ability to remove fluoride from contaminated water, and the best defluoridation capacity was evaluated as 2.21 mg/g for the H₂O₂ cement. Equilibrium modeling was performed, and the experimental data were presented according to the isotherms of Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich.

[Brucella endocarditis of native valves. Report of 3 cases]

Brucella endocarditis is a rare but a serious complication of human brucellosis. We report 3 cases, the diagnostic was suspected by the patient's history of systemic brucellosis in two cases and established by the culture of native valve material in the third. All the patients underwent surgery for non control of the infections, one patient died in immediately postoperative period by acute cardiac failure. For the other patients, there were no early or late mortality and no recurrence after a follow up of respectively 6 and 84 months. The diagnostic of brucella endocarditis needed a very high degree of clinical suspicion, it requires an early management valve replacement is in the majority of cases, followed by adequate and prolonged antibiotic treatment.

[Epidemiology of chronic arteritis of the lower limbs: multicenter study: report of 531 cases]

Arteritis is a local finding of a general disease: atherosclerosis. To define the risk factors of this disease in Tunisia, 531 patients were collected by a multicenter retrospective study between January 1998 and December 1999. Most of our patients were male with a mean age of 62 years. The most important risk factor was tobacco with an incidence of 90%. Lipids and diabetes were less common. The association of risk factors is particularly dangerous.

[Carotid stenosis: indications and therapeutic approach]

There has not been a peripheral vascular surgical procedure subject to as exquisite scruting as carotid endarterectomy. The last decade gave a new attitude after the analysis and conclusions of the North American Symptomatic Carotid Endarterectomy Symptomatic extracranial lesions were best managed with operative intervention rather than antiplatelet treatment alone. Now, in the first decade of the new millenium, we are embarking on yet another test of carotid endarterectmy--a comparison with percutaneous angioplasty and stenting, which is a most rigorous contest because endarterectomy must now withstand comparison with another "active treatment" rather than the more passive observational modality of antiplatelet therapy. The topic of the authors was to provide a panorama of the contemporay treatment of carotid disease at this pivotal point in the life cycle carotid endarterectomy.

[Thoracic hydatidosis. A review of 1619 cases]

We analyzed the cases of 1619 patients who underwent surgery for hydatidosis in a chest localization to present a review of this parasitosis, endemic in Southern Mediterranean countries. A lung localization was observed in 1527 patients (94.6%). Extrapulmonary localizations were less common (5.62%) and included 42 heart cysts, 21 primary pleural cysts, 13 diaphragm cysts, 8 mediastinum cysts and 8 ribs cysts. For pulmonary cysts the sex ratio was 1: 1 (51.46% men, 48.85% women). Mean age was 24 years. A context of hydatid exposure was present in 81.8% of cases. The diagnosis was established on the basis of associated functional signs and an opacity with regular borders on the chest x-ray. Surgical treatment was simple cystecomy in 85.9% of the cases and lung resection in 14. 1%. Operative mortality was 0.785%. Pleuropulmonary recurrence was observed in 21 patients. Thoracic and pulmonary hydatidosis is easily diagnosed and treatment is well defined. It remains however a major challenge for health care with an important social and economic impact. Prevention can only be achieved by carefully designed actions against parasite transmission.