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Indexed by:Journal Papers

Date of Publication:2020-07-15

Journal:JOURNAL OF ALLOYS AND COMPOUNDS

Included Journals:SCIE

Volume:829

ISSN No.:0925-8388

Key Words:Cemented carbide; High current pulsed electron beam (HCPEB); Surface modification; Thermal stability; Microstructure evolution

Abstract:Investigation on the thermal stability of the modified surface microstructure on WC-Co cemented carbide after high current pulsed electron beam (HCPEB) irradiation was carried out. Microstructural analysis showed that the micro-WC grains were melted and a compact microstructure was formed in the surface layer. Nano-grained cubic phase WC1-x was identified as the predominant phase in the modified layer, resulted from HCPEB-induced superfast heating, melting and re-solidification cycles. The modified specimens were subjected to annealing process at varied temperatures in an Ar ambience for 1 h. Post-annealing microstructural inspection results revealed that the modified microstructure was stable when the annealing temperature did not exceed 500 degrees C. When the annealing temperature was elevated to 600 -700 degrees C, the cubic phase WC1-x gradually transferred into two hexagonal phases, WC and W2C. Further elevating the annealing temperature up to 900 degrees C, significant amount of ternary phases, Co6W6C and Co2W4C, formed in the surface layer. The evaluation of surface microhardness indicated a strengthening effect of the annealing on the modified microstructure. The maximum microhardness (2530 HV) was obtained after annealing at 700 degrees C. (C) 2020 Elsevier B.V. All rights reserved.