Formation of gradient microstructure and mechanical properties of hot-pressed W-20 wt% Cu composites after sliding friction severe deformation

Dong, Longlong, Ahangarkani, Meysam, Zhang, Weihua, Zhang, Baochang, Chen, W. G., Fu, Yong Qing and Zhang, Y. S. (2018) Formation of gradient microstructure and mechanical properties of hot-pressed W-20 wt% Cu composites after sliding friction severe deformation. Materials Characterization, 144. pp. 325-335. ISSN 1044-5803

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Official URL: http://dx.doi.org/10.1016/j.matchar.2018.07.016

Abstract

W-based alloys are currently considered promising candidates for high heat flux components in future fusion reactors. In this paper, hot pressed W-20 wt%Cu composites were treated at room temperature using a sliding friction severe deformation (SFD) process, with a moving speed of 0.2 m/s and an applied load of 500 N. Microstructural evolution of composites after the SFD treatment was evaluated and compared with that of the untreated composites. Results showed that there was a gradient structure generated and an obvious refinement in tungsten particles size in the surface layer after the SFD process. The average particle size of tungsten in the SFD treated composites was 2.60 μm, whereas it was 4.5 μm for tungsten in the untreated composites. Fracture surfaces of the composites indicated that the SFD treatment destroyed the W skeleton and changed fracture mode from predominant inter-granular one to trans-granular one due to the decrease in contact area of W-W inter-particles. Yield strength and ultimate tensile strength of composites after the SFD treatment were 308 MPa and 553 MPa, respectively. The treated composites exhibited micro-hardness values with an average reading of about 308 HV. Analysis of the facture microstructures clearly suggested that the tungsten particles in the treated composites are consisted of dislocations and boundaries as well as dislocation tangles. The electrical conductivity of the composites was decreased from 33 IACS% to 28.5 IACS% after the SFD treatment, mainly due to loss or squeezing of copper into the inner surface.

Item Type: Article
Uncontrolled Keywords: W-Cu composites; Sliding friction treatment; Microstructure; Mechanical properties
Subjects: H300 Mechanical Engineering
J200 Metallurgy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Paul Burns
Date Deposited: 26 Oct 2018 15:28
Last Modified: 11 Oct 2019 09:53
URI: http://nrl.northumbria.ac.uk/id/eprint/36447

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