Thermal expansions and mechanical properties of electrodeposited Fe–Ni alloys in the Invar composition range

Experimentally validated inverse design of multi-property Fe-Co-Ni alloys

This study presents a machine learning (ML) framework aimed at accelerating the discovery of multi-property optimized Fe-Ni-Co alloys, addressing the time-consuming, expensive, and inefficient nature of traditional methods of material discovery, development, and deployment. We compiled a detailed heterogeneous database of the magnetic, electrical, and mechanical properties of Fe-Co-Ni alloys, employing a novel ML-based imputation strategy to address gaps in property data. Leveraging this comprehensive database, we developed predictive ML models using tree-based and neural network approaches for optimizing multiple properties simultaneously. An inverse design strategy, utilizing multi-objective Bayesian optimization (MOBO), enabled the identification of promising alloy compositions. This approach was experimentally validated using high-throughput methodology, highlighting alloys such as Fe66.8Co28Ni5.2 and Fe61.9Co22.8Ni15.3, which demonstrated superior properties. The predicted properties data closely matched experimental data within 14% accuracy. Our approach can be extended to a broad range of materials systems to predict novel materials with an optimized set of properties.

Characterization of electroless Ni-coated Fe–Co composite using powder metallurgy

This study covers composite production and characterization of powders obtained by applying the electroless Ni coating technique to Fe–Co powders by microwave sintering technique. The physical, mechanical, and electrical properties of electroless Ni-coated Fe and Co composites samples produced in different compositions by sintering magnetic materials in a microwave oven at 1,100°C were characterized. With the electroless coating technique, a uniform nickel deposit on the Fe–Co particles was coated before sintering with the precipitation procedure. A composite consisting of metallic phase, Fe–Co, and triple additions in a Ni matrix was prepared in an argon atmosphere and sintered by microwave technique. X-ray diffraction, scanning electron microscope, and impedance phase analyzer were used to obtain structural data in the temperature range of 25–40°C and to determine magnetic and electrical properties such as dielectric and conductivity. The ferromagnetic resonance was varied between 10 Hz and 1 GHz, and measurements were made to characterize the properties of the samples. Numerical findings obtained for 25% Ni composition at 1,100°C (Fe–37.5% Co) suggest that the best conductivity and hardness are obtained by adding 25Ni at 1,100°C sintering temperature.

Research on Cracking Mechanism of Early-Age Restrained Concrete under High-Temperature and Low-Humidity Environment

How to prevent the cracking of tunnel lining concrete under a high-temperature and low-humidity environment has gradually become a challenge faced by the engineering community. Actually, the concrete structure will be restrained, which easily leads to cracking. Aiming at this problem, a self-restraint device of concrete specimens was designed in this paper, which aims to more realistically simulate the restrained state of concrete structures during construction. SEM, EDS and XRD detection methods were used to study the macroscopic and microscopic properties of an early-age restrained concrete specimen under a high-temperature and low-humidity environment, and the results were compared with those of a non-restrained concrete specimen. The results show that the change in the internal relative humidity of the concrete was an extremely slow process, and the response rate of the internal humidity of the concrete was much slower than that of the temperature. A cubic curve model was used to fit the measured concrete damage degree with the loading age, and the fitting effect was good. Under the environment of high temperature and low humidity, the loading age from the 0.6th day to the 1st day was the period of a relatively large fluctuation in the concrete temperature and humidity, and the restraint would aggravate the damage of the concrete. The damage degree increased with the increase in the loading age, the microcracks gradually increased and, finally, macrocracks were formed. The restraint effect was to intensify the formation of microcracks, affect the hydration of the cement at the micro level and, finally, increase the risk of concrete cracking perpendicular to the restrained direction at the macro level. The research results may provide guidance for research on the cracking mechanism of tunnel lining concrete constructed under a high-temperature and low-humidity environment.

Rapid Electrodeposition of Fe–Ni Alloy Foils from Chloride Baths Containing Trivalent Iron Ions

This work presents the rapid electrodeposition of Fe–Ni alloy foils from chloride baths containing trivalent iron ions at a low pH (<0.0). The effect of the concentration of Ni2+ ions on the content, surface morphology, crystal structure, and tensile property of Fe–Ni alloys is studied in detail. The results show that the co-deposition of Fe and Ni is controlled by the adsorption of divalent nickel species at low current density and the ionic diffusion at high current density. The current density of preparing smooth and flexible Fe–Ni alloy foils is increased by increasing the concentration of Ni2+ ions, consequently the deposition rate of Fe–Ni alloy foils is increased. For example, at 0.6 M Ni2+ ions, the current density can be applied at 50 A·dm−2, along with a high deposition rate of ~288 μm·h−1.