Mechanism for magnetic field induced structural relaxation and accompanying fracture toughness improvement of the thermal spraying coating

• Published in: Materials & design 2022-11, Vol.223, p.111113, Article 111113
• Main Authors: Qian, Chengkai, Liu, Qu, Xiong, Xiyao, Ye, Bangjiao, Li, Zhiyong, Li, Kejian, Ying, Shaojun, Zhang, Hongjun, Huang, Dongmei, Zhang, Xu, Cai, Zhipeng
• Format: Article
• Language: English
• Subjects: Cemented carbide coating; Fracture toughness; Pulsed magnetic treatment; Structural relaxation
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2022.111113

[Display omitted] •Pulsed magnetic treatment is firstly employed to improve the fracture toughness of the commercially available thermal spraying coating.•Structural relaxation of the binder is observed along with the annihilation of large free volume holes.•Mechanism of the pulsed magnetic treatment on the structural relaxation is explained at the atomic level.•The method is easy to be applied to various functional materials to diminish inner defects. Fracture toughness is critical for the fatigue life of the cemented carbide coatings widely used in the aviation fields, and the development of an economical and effective post-treatment method is in demand. In this research, pulsed magnetic treatment was applied to the thermal spraying WC-10Co4Cr coating with a 17.7% improvement in its fracture toughness, and the strengthening mechanism was further investigated. Microstructure characterization indicates that structural relaxation took place in the amorphous Co binder, and the annihilation of some free volume holes mainly contributes to the mechanical property enhancements. Atomic migration related to the structural relaxation was further explained in terms of the magnetic field induced intersystem crossing. Improvement of both the nano-hardness and elastic modulus of the Co binder was also observed as a result of structural relaxation. This work provides a possible non-thermal post-treatment method for not only the different kinds of cemented carbide coatings but also other amorphous functional materials sensitive to crystal defects.