Huo Yuying,Wang Zhengyan,Zhang Yanlan,Wang Yongzhen
High-entropy design is attracting growing interest as it offers unique structures and unprecedented application potential for materials. In this article, a novel high-entropy ferrite (CoNi) x /2 (CuZnAl) (1− x )/3 Fe 2 O 4 ( x = 0.25, 0.34, 0.40, 0.50) with a single spinel phase of space group \(Fd\bar{3}m\) was successfully developed by the solid-state reaction method. By tuning the Co–Ni content, the magnetic properties of the material, especially the coercivity, changed regularly, and the microwave absorption properties were improved. In particular, the effective absorption bandwidth of the material increased from 4.8 to 7.2 GHz, and the matched thickness decreased from 3.9 to 2.3 mm, while the minimum reflection loss remained below −20 dB. This study provides a practical method for modifying the properties of ferrites used to absorb electromagnetic waves.
Fine grained WC-Co-Ni cemented carbides with a low binder content have been successful manufactured via the powder metallurgy method. The WC-Co-Ni composite powder with homogeneous distributions of Co and Ni was synthesized by chemical co-precipitation with the raw materials of WC powder, oxalic acid and chlorides of Co and Ni. In this study, the effects of cobalt and nickel contents on the properties of cemented carbides were investigated systematically. The experimental results demonstrated that the alloy prepared by vacuum sintering had uniform grain size distribution and no abnormal growth of WC grains. When the cobalt content was 4 wt% and 5 wt%, the obtained composites almost completely consolidated with excellent hardness and fracture toughness. Among them, for the sample WC-4 wt%Co, the relative density could reach 99.37%, and the Vickers hardness and fracture toughness were 2010 HV 30 and 8.55 MPa·m 1/2 , respectively. When Ni was added to replace part of Co, the relative density of WC-Co-Ni decreased and the fracture toughness was improved without basically sacrificing the hardness. For the sample WC-2 wt%Co-2 wt%Ni, the hardness decreased to 1921 HV 30 , while the fracture toughness increased to 8.97 MPa·m 1/2 .
危险品化学品经营许可证（带存储）