Amplitude-dependent internal friction in AZ31 alloy sheets submitted to accumulative roll bonding

Fine grained magnesium alloy AZ31 sheets were submitted to the accumulative roll bonding (ARB). After ARB, the microstructure of samples was refined, and the sheets exhibited pronounced texture. The amplitudedependent internal friction (ADIF) was measured at room temperature. Microstructure changes as the increased dislocation density, grain size refinement, twins, and texture influenced the ADIF. A significant anisotropy of the properties was observed. Experimental results are discussed on the base of physical mechanisms responsible for internal friction.Дрібнозернисті листи магнієвих сплавів AZ31 були піддані накопичувальному з’єднанню вальцюванням (ARB). Після застосування ARB мікроструктура зразків ставала більш фрагментованою, і в листах спостерігалась яскраво виражена текстура. Амплітудно-залежне внутрішнє тертя (АЗВТ) вимірювали при кімнатній температурі. Зміни мікроструктури, такі як збільшення щільності дислокацій, зменшення розміру зерна, поява двійників та текстури, приводили до змін АЗВТ. Спостерігалась суттєва анізотропія вивчених властивостей. Експериментальні результати обговорюються на базі відомих фізичних механізмів, що відповідають за внутрішнє тертя.Мелкозернистые листы магниевых сплавов AZ31 были подвергнуты накопительному соединению прокаткой (ARB). После применения ARB микроструктура образцов становилась более фрагментированной, и в листах наблюдалась ярко выраженная текстура. Амплитудно-зависимое внутреннее трение (АЗВТ) измеряли при комнатной температуре. Изменения микроструктуры, такие как увеличение плотности дислокаций, уменьшение размера зерна, появление двойников и текстуры, приводили к изменениям АЗВТ. Наблюдалась существенная анизотропия изученных свойств. Экспериментальные результаты обсуждаются на основе известных физических механизмов, отвечающих за внутреннее трение

Build Size and Orientation Influence on Mechanical Properties of Powder Bed Fusion Deposited Titanium Parts

This paper explores the influence of sample thickness and build orientation on the microstructure and mechanical properties of electron beam melting (EBM) additive manufactured Ti-6Al-4V titanium alloy and compared to previously published work on SLM-processed material. In particular, the various mechanical properties (tensile yield strength, ultimate tensile strength) were investigated with attempts to correlate with various microstructural features, including lamellae thickness, porosity and the size of prior-beta grains. However, it is shown that the surface exerts a dominant effect on mechanical properties with as-deposited surfaces. These observations provide the possibility for the further improvement of processing/property relations with as-deposited surfaces

The antimicrobial activity of honey, bee pollen loads and beeswax from Slovakia

The aim of this study was to test the antimicrobial activity of propolis, bee pollen loads and beeswax samples collected in the year 2009 from two locations in Slovakia to pathogenic bacteria, microscopic fungi and yeasts. The antimicrobial effect of the bee product samples were tested using the agar well diffusion method. For extraction, 99.9% and 70% methanol (aqueous, v/v) and 96% and 70% ethanol (aqueous, v/v) were used. Five different strains of bacteria, i.e. Listeria monocytogenes ccM 4699, Pseudomonas aeruginosa ccM 1960; Staphylococcus aureus ccM 3953; Salmonella enterica ccM 4420, Escherichia coli ccM 3988, three different strains of microscopic fungi, Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, and seven different strains of yeasts Candida krusei, Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, Geotrichum candidum, Rhodotorula mucilaginosa, were tested. After 48 hours S. aureus was the bacterium most sensitive to the 70% ethanol extract of pollen, A. fumigatus was the most sensitive microscopic fungus (70% ethanol) and C. glabrata the most sensitive yeast (70% methanol). Microorganisms most sensitive to propolis extracts were L. monocytogenes, A. fumigatus (70% ethanol) and G. candidum (70% methanol). Most sensitive to beeswax extracts were E. coli, A. niger and C. tropicalis

Magnesium reinforced with inconel 718 particles prepared ex situ-microstructure and properties

10.3390/ma13030798Materials13379

Pressure vessel design simulation: Implementing of multi-swarm particle swarm optimization

The new era knowledge of optimization algorithm is massively boosted recently. Among several optimization models, multi-swarm approach has been proposed most recently for balancing the exploration and exploitation capability through the Particle Swarm Optimization (PSO) algorithm. The proposed multi-swarm model which is called Meeting Room Approach (MRA), is tested and evaluated based on solving normal and large-scale problems. In the current research, the feasibility of the proposed Multi-Swarm Particle Swarm Optimization (MPSO) is adopted to simulate mechanical engineering problem namely pressure vessel design (PVD). The results indicated the potential of the proposed MPSO model on simulating the PVD problem with optimum solution over the standalone PSO. Further, the current study results authenticated against other famous meta-heuristics. Overall, MPSO reported an excellent optimization solution with fast convergence learning process