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Suppression of Abnormal Grain Growth in WC–Co via Two‐Step Liquid Phase Sintering
Author(s) -
Yang DongYeol,
Yoon Duk Yong,
Kang SukJoong L.
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.04198.x
Subject(s) - sintering , materials science , microstructure , grain growth , grain size , metallurgy , liquid phase , phase (matter) , chemistry , physics , organic chemistry , thermodynamics
Microstructure refinement via two‐step sintering and its mechanism have been investigated in 92WC–8Co (wt%) alloys. Samples were prepared using conventional and two‐step sintering techniques. For conventional sintering, the powder compacts were sintered at 1400°C for various times. For two‐step sintering, the powder compacts were heated up to 1500°C, immediately cooled down to 1400°C, and held for various times at 1400°C. In the conventional sintering, >99% relative density (RD) was obtained after 2 h; however, abnormal grain growth (AGG) occurred. In the two‐step sintering, >99% RD was obtained without AGG for up to 2 h sintering times at 1400°C, showing a uniform microstructure with fine grains of ∼0.6 μm in average size. Computer calculation suggested a reduction of the maximum driving force for grain growth right after the first‐step sintering at 1500°C. Retardation of AGG in two‐step sintering is thus attributed to the change in average grain size and size distribution after the first step of sintering.