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Elevated‐Temperature Toughness and Hardness of a Hot‐Pressed Al 2 O 3 —WC—Co Composite
Author(s) -
Tai WeonPil,
Watanabe Tadahiko
Publication year - 1998
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.1151-2916.1998.tb02328.x
Subject(s) - materials science , fracture toughness , composite material , composite number , atmospheric temperature range , softening , graphite , brittleness , toughness , physics , meteorology
The fracture toughness and hardness of an Al 2 O 3 80WC10Co composite were investigated in air at elevated temperatures. The primary phases in the composite were WC, α‐Al 2 O 3 , and Co 3 W 3 C, but small amounts of Co and C (graphite) appeared at elevated temperatures, related to decomposition of the Co 3 W 3 C phase. The fracture toughness of the composite was constant with increasing temperature up to 330°C and then increased in the range 400° to 550°C. A transition of brittle to ductile behavior occurred at about 700°C. The enhancement of fracture toughness at elevated temperature is attributed to the decomposition of Co 3 W 3 C to Co and C, and enhanced crack deflection and bridging. Decreases in hardness with increasing temperature are attributed to the softening of WC matrix and decomposition of Co 3 W 3 C.