In this paper, the microstructure and properties of MX246A alloy laser double-sided welding were studied. Different alloy welding structures were obtained under different laser powers, and the fine-grain zone, columnar-grain zone, and equiaxed-grain zone in the welding structure were analyzed. According to the results of SEM, it was found that the width of the surface fine-grain zone was generally thin, which had little effect on the quality and properties of the welded joint. The quality and properties of the welded joint mainly depended on the proportion of columnar-grain zone and equiaxed- grain zone, as well as the grain size. Moreover, with the increase of laser power density, the number of columnar grains decreased, while the number of equiaxed grains increased. The grain size of equiaxed grains became smaller, and the structure became denser, resulting in better mechanical properties. The double-sided welding was subjected to high-temperature and room-temperature tensile tests. The Laser welding double-sided tensile properties test showed that the tensile strength was 555 MPa at room temperature and 400 MPa at 1000 °C under the laser power intensity of 1704 W/mm2 . The study revealed that MX246A alloy exhibited superior tensile properties and microhardness than the substrate, while the microstructure demonstrated excellent high-temperature durability.
In this work, the structural stability, fracture toughness, and thermodynamic properties of Co30Ni30Fe20Cr20 high-entropy alloy (HEA) has been investigated by using first-principles calculations combined with special quasi-random structures. The calculated lattice constant of 3.485 Å was in good agreement with the experiments, and the obtained formation enthalpy value of −1.17 eV/atom indicated that this particular HEA was stable. The results showed that the Fracture energy of the [111] direction was much lower than the [001] and [110] directions. Therefore, the bond strength of the [111] direction was inferred to be the weakest. Finally, the entropy, internal energy, and specific heat capacity of the Co30Ni30Fe20Cr20 HEA increased with increasing temperature, while the free energy and bulk modulus decreased. Thus, the results obtained in this work could be used for studying and designing high performance CoCrFeNi HEAs.
Due to its lightweight, high strength, good machinability, and low cost, aluminum alloy has been widely used in fields such as aerospace, automotive, electronics, and construction. Traditional manufacturing processes for aluminum alloys often suffer from low material utilization, complex procedures, and long manufacturing cycles. Therefore, more and more scholars are turning their attention to the laser powder bed fusion (LPBF) process for aluminum alloys, which has the advantages of high material utilization, good formability for complex structures, and short manufacturing cycles. However, the widespread promotion and application of LPBF aluminum alloys still face challenges. The excellent printable ability, favorable mechanical performance, and low manufacturing cost are the main factors affecting the applicability of the LPBF process for aluminum alloys. This paper reviews the research status of traditional aluminum alloy processing and LPBF aluminum alloy and makes a comparison from various aspects such as microstructures, mechanical properties, application scenarios, and manufacturing costs. At present, the LPBF manufacturing cost for aluminum alloys is 2–120 times higher than that of traditional manufacturing methods, with the discrepancy depending on the complexity of the part. Therefore, it is necessary to promote the further development and application of aluminum alloy 3D printing technology from three aspects: the development of aluminum matrix composite materials reinforced with nanoceramic particles, the development of micro-alloyed aluminum alloy powders specially designed for LPBF, and the development of new technologies and equipment to reduce the manufacturing cost of LPBF aluminum alloy.
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