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Grain refinement in laser remelted Mg-3Nd-1Gd-0.5Zr alloy
摘要： Columnar grains are normally favoured with the high cooling rate and steep thermal gradient in laser-based additive manufacturing. Here, we demonstrate that ?ne, fully equiaxed grains can be achieved in Mg-3Nd-1Gd-0.5Zr (EV31) alloy by laser surface remelting. The grains in the melt pool are remarkably re?ned from 74 μm to 3.5 μm, which can be attributed to the growth restriction effect, i.e. the constitutional supercooling formed by Zr solute during solidi?cation in combination with the high cooling rate imposed by laser surface remelting. This novel ?nding could be applied for the control of grain morphology and alloy design for additive manufacturing applications.
关键词： Solidi?cation microstructure,Grain re?ning,Laser treatment,Magnesium alloys,Rapid solidi?cation
更新于2025-09-23 15:19:57
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Computer aided design of the laser dieless drawing process of tubes from magnesium alloy with take into account ductility of the material
摘要： Paper is devoted to the laser dieless drawing of the tubes made of magnesium alloy ZEK100. Important limitation of this process is a low ductility of magnesium alloys. The purpose of this work was the development and implementation into the FEM code, the ductility model of ZEK100 magnesium alloy and experimental validation of proposed methodology of process design. Ductility and flow stress models were developed based on tension and compression tests in temperature interval 20-350 °C. As result of this work, the technological diagrams for determination of diameter of tube after laser dieless drawing process were obtained.
关键词： Ductility,Dieless drawing,Tube,Magnesium alloys
更新于2025-09-12 10:27:22
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Optimization of production process of Mg tubes produced with laser dieless drawing method and related microstructural analysis
摘要： This contribution deals with a laser dieless drawing method in which tubes (AZ31 magnesium alloy) with small dimensions are produced from previously extruded tubes with a larger diameter. The process involves local laser heating of a tube with concurrent drawing and rotation of a sample. The control parameters need to be optimized in order to get a good quality tube with low damage and regular diameter. Here, a previously developed finite element (FE) model is used for the numerical optimization. The optimization itself is multi-objective, maximizing the uniformity of the resulting tube but concurrently, minimizing its critical deformation. Since one run of the FE code lasts for several days, an approximation by a Radial Basis Function meta-model (surrogate) is used. Results reveal that there is only a very limited number of combinations of parameters leading to a uniformly shaped tubes. Finally, tubes produced with optimized parameters are analyzed from the microstructural point of view.
关键词： Laser dieless drawing process,Microstructural analysis,Optimization,Numerical modeling,Magnesium alloys
更新于2025-09-12 10:27:22
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Efficient Interfacial Solar Steam Generator with Controlled Macromorphology Derived from Flour via “Dough Figurine” Technology
摘要： Poor corrosion and wear resistance of magnesium (Mg) alloys restrict their applications. Herein, corrosion and wear-resistant films are formed upon Mg alloy AZ31 through a micro-arc oxidation (MAO) process in silicate electrolyte in the presence of carbon spheres (CS). Surface morphology, chemical composition, corrosion resistance, hardness, and coefficient of friction (CoF) of the MAO coatings are investigated using field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrometry (FTIR), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical and hydrogen evolution measurements, automatic micro-hardness testing, and reciprocating tribometer, respectively. Results demonstrate that the surface morphology and hardness of MAO coatings vary with the concentration of CS. The presence of CS results in an increased coating thickness from 8.0 (cid:1) 1.8 to 12.2 (cid:1) 1.8 μm, mean pore size from 0.7 (cid:1) 0.1 to 1.9 (cid:1) 0.1 μm, open porosity of MAO coating from 4.2 (cid:1) 0.4 to 5.6% (cid:1) 1.1%, and coating hardness from 347.0 (cid:1) 59.0 to 853.0 (cid:1) 67.3 Vickers-hardness (HV). Furthermore, CS-modified MAO coatings lead to improved corrosion resistance in comparison with that of the neat MAO counterparts. Moreover, the high hardness and formation of SiC of CS-modified coatings lead to a low and stabilized CoF, which implies an enhanced wear resistance.
关键词： micro-arc oxidation,coatings,corrosion resistance,carbon spheres,magnesium alloys
更新于2025-09-11 14:15:04
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Influence of laser surface melting on the properties of MB26 and AZ80 magnesium alloys
摘要： In the present investigation, laser surface melting (LSM) was performed on MB26 and AZ80 magnesium alloys and their surface properties were evaluated. The finite element method (FEM) was used to calculate the resulting temperature during the laser surface melting process. The melted layer average thickness values were about 296 and 190 μm for MB26 and AZ80 alloys, respectively and the variation in the thickness is mainly attributed to the absorption in laser energy. The average grain size of the LSMed MB26 alloy was decreased about 14.5 times and AZ80 had very finer grains than the MB26 along with the fine distribution of second phases. Further, the X-ray diffraction results revealed that the second phase intensities were decreased in both the alloys due to their dispersion. The laser absorption efficiency of MB26 was higher due to the higher plasma attachment during LSM process, thereby has higher melt layer thickness compared to AZ80. The refined microstructure of the melted layer resulted in an increase of micro-hardness up to 110 Hv. Potentiodynamic polarization test results revealed that the corrosion current density (icorr) values of the LSMed MB26 and AZ80 alloys were decreased about 1.8 and 2.5 times, respectively compared to the as-received alloys. A variation in solidification rates of the melt pool due to the alloying elements were attributed to an improvement in the surface and electrochemical properties.
关键词： Corrosion,Polarization,Laser surface melting,Hardness,Magnesium alloys
更新于2025-09-11 14:15:04