214 research outputs found
Growth and Development of the Lymphoid Organs as Affected by Inorganic and Organic Zinc in Broilers Chickens
No full textZinc is one of the important minerals that affect the immune system. It should be incorporated in the diet since the effects of deficiency are very pronounced. However, the levels and sources are still unknown particularly in the growth and development of the lymphoid organs. Hence, this study was conducted. Two experiments were conducted following a completely randomized design for a period of 36 days. Experiment 1 utilized zinc oxide while 2 made used of zinc methionine. Results revealed that the different levels of zinc oxide did not affect the average weight and number of lymphatic nodules of the Bursa of Fabricius and thymus. The same organs involuted between 15-28 days and 11-21 days, respectively. The spleen, however, was unaffected. In Experiment 2, it shows that the average weight and number of lymphatic nodules of the bursa of Fabricius and thymus were not affected by the different levels of zinc methionine. Bursa involuted from days 8-28 while thymus, between 11-21 days. Increasing spleen's weight pattern was noted only in the control group beginning on day 11 and peak on day 28. The study concludes that the growth and development of the lymphoid organs were not affected by zinc inclusion in the diet. It recommends that supplementation must be accompanied by good management practices
Simultaneously Improved Bendability and Strength of Al–Mg–Si–Cu–Zn Alloys by Controlling the Formation and Evolution of Primary Fe-Rich Phase
No full textIn present work, the formation, evolution, and distribution of the primary Fe-rich phase in an Al–Mg–Si–Cu–Zn–Fe–Mn alloy are coupling controlled by ultrasonic melt treatment (USMT) and thermomechanical processing (TMP). It is shown in the results that the size of grains and Fe-rich phase in the as-cast state can be greatly reduced by the applied optimum USMT at 680 °C. Additionally, the transformation rate of β-Fe-rich phase to α-Fe-rich phase can be also enhanced. After the coupling control of USMT and TMP, the number density and distribution uniformity of multiscale Fe-rich particles can be greatly increased or improved, which contributes to the fine-grained recrystallization microstructure and weakened texture. Finally, compared with the 6xxx series Al alloys (such as AA6016 and AA6111), the alloy sheet in the pre-aging state exhibits substantially improved bendability and strength (the plastic strain ratio and tensile strength are 0.67 and 304 MPa, respectively). The effect of USMT on the formation and transformation of primary Fe-rich phase and the mechanisms of improved bendability and strength are deeply discussed.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Maria Santofimia Navarr
Surface Oxidation and Wettability of Fe–Mn and Fe–Mn–Si-Alloyed Steel After Annealing
No full textThe surface oxidation and wettability of Mn and Si-alloyed steel after annealing at different conditions are studied with scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and a so-called de-wetting method. After exposure at 950 °C for 1 hour in an Ar + 5 vol pct H2 gas atmosphere with dew points (DP) ranging from – 40 °C to 10 °C, oxides were observed along the grain boundaries or dispersed on the surface for the Fe–1.8 Mn steels while a continuous oxides layer was formed on Fe–1.9 Mn–0.94 Si steels (composition in weight fractions). The oxides formed at different DPs were predicted based on thermodynamic calculations. (Fe,Mn)O was formed on Fe–1.8 Mn steel at the whole range of DPs, while the oxide phase on Fe–1.9 Mn–0.94 Si steel depends on the DP. At low-DP SiO2 were formed and with increasing the DP (Fe,Mn)SiO3 or (Fe,Mn)SiO3 + (Fe,Mn)2SiO4 were formed and finally (Fe,Mn)2SiO4 were formed. An increase of the fraction of Fe in the oxide with increasing DP for both steels was observed with XPS analysis. As a measure for the surface wettability, the contact angle of Pb droplets on the annealed steels surfaces was determined with SEM and image analysis software. Also, the contact angle of Pb on pure Fe and on the Mn and Si alloyed steels free of surface oxides was measured for comparison. The results show that the contact angle of Pb on the steel surfaces after annealing decreases with increasing DP. This improved wettability with increasing dew point is related to the Fe fraction of the oxides formed on the surface.Team Kevin RossiTeam Maria Santofimia NavarroTeam Marcel Herman
Effect of the heat treatment on the microstructure, magnetism and magnetocaloric effect in Fe-rich (Mn,Fe)<sub>y</sub>(P,Si) melt-spun ribbons
No full textThe effect of the heat treatment on the magnetism, magnetocaloric effect and microstructure formation has been systematically studied in Fe-rich (Mn,Fe)y(P,Si) melt-spun ribbons (1.80 ≤ y ≤ 2.00). XRD, SEM and EDS measurements demonstrate that a metal deficiency prompts the stable (Mn,Fe)Si phase, whereas in the metal-rich region the (Mn,Fe)3Si phase is formed. It is found that the annealing temperature influences the composition and lattice parameters of the (Mn,Fe)y(P,Si) alloys, which greatly affects the Curie temperature (TC). For the optimal metal/non-metal ratio y the magnetic entropy change (|ΔSm|) is found to increase from 5.5 to 15.0 Jkg−1K−1 in a magnetic field change of 2 T by varying the annealing temperature from 1313 to 1433 K, indicating an enhancement of the first-order magnetic transition (FOMT). The presented results reveal that the secondary phase and magnetic properties in the (Mn,Fe)y(P,Si) system can be tuned by varying the annealing temperature and by adjusting the metal/non-metal ratio y.RST/Fundamental Aspects of Materials and EnergyTeam Maria Santofimia Navarr
Synergy of Ni micro-alloying and thermomechanical processing in Al–Mg–Si–Cu–Zn–Fe–Mn alloys with enhanced bendability
No full textSynergy of Ni micro-alloying and thermomechanical processing on the phase distribution, formability and bendability of Al–Mg–Si–Cu–Zn–Fe–Mn alloys was systematically studied in this paper. With the addition of micro-alloying Ni, the Ni-containing Fe-rich phase can be formed, which not only serves as nucleation sites of Mg–Si precipitates (such as, Q phase) during the casting process, but also improves the uniform distribution level of Fe-rich phases after homogenization. The formability and bendability of Ni-containing alloy can be both improved to a certain level due to the positive effect of Ni micro-alloying. In comparison, if increasing the cold rolling deformation between hot rolling and annealing, the distribution of multi-scale Fe-rich phases can be significantly improved based on the synergy of Ni micro-alloying and thermomechanical processing. And finally, this improvement further results in the great improvements in the microstructure, texture, formability (average r = 0.688, △r = −0.09) and bendability of the alloy together. Based on the microstructure evolution, the synergy mechanism of Ni micro-alloying and thermomechanical processing is put forward in this paper.Team Maria Santofimia Navarr
Engineering austenite/martensite mesostructured materials by controlled localised laser treatments in a Fe–Ni–C alloy
No full textLocalised laser treatments enable the creation of sophisticated austenite/martensite mesostructures in Fe–Ni–C steel with the potential of achieving enhanced mechanical performance. The control of phase topology is essential to modify the properties of these structures on demand and requires a profound understanding of the effect of the processing parameters on the development of the different phases upon the application of laser treatment. In this work, the microstructure evolution under exceptional gradients in temperature and heating rates is thoroughly investigated. The extent of the laser-affected zone and the heat input were tailored by varying laser parameters and specimen thickness, based on a model that considers transient material properties and the coupling between temperature and microstructure. The predicted temperature fields resulted in a complex interplay between martensite to austenite phase transformation and martensite tempering. Considering the high heating rates of up to 25000 K/s and the observed microstructures, it is suggested that austenite was formed by a pseudo-displacive mechanism and subsequently fully recrystallised in the zones most directly affected by the laser heat source. A smooth strength transition from austenite to martensite, affected by the laser parameters, could be exploited for more effective deformation mechanisms and improved material mechanical properties.Team Marcel HermansTeam Maria Santofimia Navarr
Microstructure evolution and mechanical behavior of Fe–Mn–Al–C low-density steel upon aging
No full textThis study focuses on the microstructure's evolution upon different aging conditions of a high-strength low-density steel with a composition of Fe–28Mn–9Al–1C. The steel is hot rolled, subsequently quenched without any solution treatment, and then aged under different conditions. The microstructure of the samples was studied by means of Scanning Electron Microscopy, Electron Backscatter Diffraction, and Transmission Electron Microscopy. The aging treatment leads to the formation of an ordered face-centered cubic L12 phase named κ-carbide. This study aims to characterize the formation and growth of these κ-carbides qualitatively and quantitatively under different aging conditions. Then, an effort is made to relate the fraction and size of this phase with the tensile properties of the steel to determine the optimal aging conditions that will lead to a good combination of strength and ductility. It has been found that the κ-carbides start to form intragranularly through concentration fluctuations of aluminum and manganese inside the austenite grain. Then, with the process of spinodal decomposition, they grow in size coherently with the matrix. During this process, the strength and hardness of the steel increase while maintaining a relatively high elongation. The best combination of high strength and ductility was achieved at the aging condition of 8 h at 550 °C with an ultimate tensile strength up to 1157 MPa and total elongation of 51%. Increasing the aging temperature and time, κ-carbides start to form intergranularly, lose their coherency with the matrix and severely compromise the hardness and strength. The shearing of the carbides during deformation is also studied.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Maria Santofimia Navarr
Effect of Co and Ni doping on the structure, magnetic and magnetocaloric properties of Fe-rich (Mn,Fe)<sub>2</sub>(P,Si) compounds
No full textThe effect of Co and Ni doping on the structure, magnetic and magnetocaloric properties of Fe-rich (Mn,Fe)2(P,Si) compounds was studied. With increasing Co and Ni content, both the Curie temperature (Tc) and the thermal hysteresis (ΔThys) decreased, whereas the hexagonal P-62 m crystal structure was maintained. A pronounced reduction in hysteresis was observed upon Co doping, while a significant reduction in Curie temperature was found upon Ni doping. Mössbauer spectroscopy measurements and DFT calculations indicated the substitution of Fe at the 3f site for both Co and Ni doping. Rietveld refinement of the X-ray diffraction data showed that Co substitute atoms in the main phase and the impurity phase, while Ni exhibits an affinity to the main phase. Magnetization measurements on the Co doped samples revealed an increase in magnetization for 2 at.% of Co, followed by a decrease for higher concentrations. DFT calculations showed that the magnetic moment on the 3f site is enhanced by Co substitution, whereas an opposite trend was observed for Ni substitution.RST/Fundamental Aspects of Materials and EnergyRID/TS/Instrumenten groepTeam Maria Santofimia Navarr
Effects of Different levels of Zinc in the Performance and Meat Zinc Contents of Broilers
No full textZinc is one of the most deficient microminerals. For poultry, NRC (1994) recommended 40 ppm only but, commercial feeds contain more than 100 ppm resulting to toxicity. Zinc oxide is commonly used inorganic forticant but, its safety is questionable compared to organic counterpart. Generally, the study aimed to determine the effects of different levels of zinc oxide and zinc methionine in the performance of broilers and their meat content at 36 and 42 days. To address the latter, two experiments (experiment 1, zinc oxide and experiment 2, zinc methionine) were conducted and gathered data were analysed using ANOVA. Results showed that in both experiments, the performance and meat zinc contents were not affected but, the parts were affected showing highest zinc content in the liver, followed by the thigh and legs, and the wings. Lowest amount was noted in the breast. Fortification, up to 36 days of feeding was found to be enough. In fortification programs, it is recommended to use organic minerals
Theoretical aspects of spinodal decomposition in Fe-C
No full textCarbon redistribution is known to occur during room temperature aging of Fe-C martensite. One of the proposed mechanisms in the literature by which carbon redistributes is spinodal decomposition, a thermodynamically driven reaction in which the alloy undergoes separation into carbon-rich and carbon-poor regions, giving rise to modulations in carbon concentration. Despite the substantial experimental evidence supporting the occurrence of spinodal decomposition in Fe-C, its theoretical formulation requires attention. In the present study, a theoretical framework based on the regular solution model is built for evaluating the thermodynamics of the Fe-C system, with particular emphasis on the interstitial nature of carbon atoms within the ferrite lattice. Assuming a defect-free lattice, the model explains a miscibility gap in the Fe-C system. The limitations of the current model are critically evaluated.(OLD) MSE-3Materials Science and Engineerin
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