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Materials with Magnetic-X Effects
Published in Chen Wu, Jiaying Jin, Frontiers in Magnetic Materials, 2023
The large magnetostriction of FeGa alloy is dependent on the [100] texture, which is also the easy growth direction and easy magnetization direction. Consequently, the main preparation method of FeGa alloy is directional solidification, involving the Bridgman method, the Float zone melting method and the Czochratski method. A directionally growth rate of 22.5 mm/h generates the polycrystalline Fe72.5Ga27.5 alloy with a near [100] texture and a large λs of 271 ppm (Srisukhumbowornchai and Guruswamy, 2001). Under an optimum directional solidification condition, satisfactory tensile fracture strain of 12.5% and λs of 387 ppm have been achieved for the Fe81Ga19 alloy doped with trace amount of Tb (0.05 at%) (Wu et al., 2019). Incorporating the third component Pr (0.20 at%) has also been reported to increase the magnetocrystalline anisotropy and strengthen the transverse magnetostriction up to 800 ppm (He et al., 2016).
Study and Control of Shrinkage in Gearbox Sand Casting Using Simulation and Experimental Validation
Published in R.S. Chauhan, Kavita Taneja, Rajiv Khanduja, Vishal Kamra, Rahul Rattan, Evolutionary Computation with Intelligent Systems, 2022
Sarabjit Singh, Rajesh Khanna, Neeraj Sharma
Reynolds number is directly related to the molten metal turbulence. Turbulence is the indication of non-smooth cavity filling and causing defects such as shrinkage porosity. This will help in redesigning the casting gating and feeding system. As a thumb rule, porosity value exceeding 10% in numerical simulation may be taken as a basis for carrying the further improvement (on the basis of Indian Foundries data using MAGMAS software. With the optimum design of the casting gating and feeding system, defects such as shrinkage porosity can be reduced by ensuring proper directional solidification in the casting. In the study of MAGMAS key performance indicators (KPIs), the input parameters may be taken as pouring temperature, metal chemical composition, green sand properties, and dimensions of the casting gating and feeding system. Casting filling results will give values of metal pressure, air pressure, air entrapment, sand inclusion, and mold erosion at different levels of filling temperature and molten metal velocity. Casting solidification results will give values of fraction liquid, hotspot, sand burn, sand penetration, and shrinkage porosity. Input parameters in terms of sand properties (sand permeability, moisture content, etc.), chemical composition of molten metal, and casting gating and feeding system dimensions (sprue size, runner size, ingate size, etc.) are used to predict various output parameters in terms of location and intensity of shrinkage porosity, metal temperature, metal velocity, and metal air pressure.
Solids, Liquids and Solidification
Published in Alan Cottrell, An Introduction to Metallurgy, 2019
Fig. 13.8 shows in a simple way how the structure of a solid metal develops by solidification of the liquid. First, dendrites grow outwards from each crystal nucleus until they meet other dendrites from neighbouring nuclei. Then the remaining liquid crystallizes on the dendrites until all is solid. This produces a polycrystalline structure, with one crystal from each nucleus. It is possible with care to grow single metal crystals (e.g. by slow directional solidification along a thin column of a pure liquid metal) but under ordinary conditions of metal casting many nuclei are formed and grow into crystals.
Experimental study of making Sn-10 wt%Pb alloy by using directional solidification under different magnetic field arrangements
Published in Journal of the Chinese Institute of Engineers, 2020
Timothy Alfred Wu, Long-Sun Chao
The directional solidification (DS) process enables grain orientation to be put in order along a specific direction. This process will decrease grain boundary (G.B.), which may improve the mechanical or electrical properties of materials. Directional solidification techniques are often used in the manufacturing of nickel-based superalloy turbine blades or multicrystalline silicon solar cells (Freche, Waters, and Ashbrook 1968; Franke et al. 2002; Kakimoto 2009). To obtain higher turbine entry temperature and increase the efficiency of engines, mechanical properties of turbine blades need to be further improved. To enhance performances can be realized via the development of the directional solidification process (Elliott et al. 2004; Liu et al. 2010; Wang et al. 2017). Casting multicrystalline silicon solar cells is widely used in the photovoltaic industry. To fabricate multicrystalline silicon solar cells economically, with high efficiency, based on directional solidification has become the mainstream in the photovoltaic industry (Wu et al. 2008; Zhang et al. 2011; Yang et al. 2015).