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Preliminary study of the crack healing and strength recovery of Al 2 O 3 ‐matrix composites
Author(s) -
JUN L.,
ZHENG Z. X.,
DING H. F.,
JIN Z. H.
Publication year - 2004
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.2004.00725.x
Subject(s) - materials science , eutectic system , indentation , composite material , annealing (glass) , ceramic matrix composite , ceramic , microstructure
This study focused on the crack‐healing behaviour of three commercial Al 2 O 3 –ceramic‐matrix composites: TiC P /Al 2 O 3 , ZrO 2 /Al 2 O 3 and SiC W /Al 2 O 3 . Vickers indentation was used to introduce surface flaws with different loads of 49, 98 and 196 N. Then the cracked specimens were annealed in air for 1 h at 1000, 1200 and 1400 °C. The annealing treatment was also conducted at 1200 °C in vacuum for 1 h. Results showed that the annealing treatments increased the indentation strength, but the extent of the increase was different. When annealed in air, the main crack‐healing mechanism of TiC P /Al 2 O 3 and SiC W /Al 2 O 3 composites was chemical reaction. When annealed in vacuum, stress relaxation caused much less strength recovery. The main crack‐healing mechanism of ZrO 2 /Al 2 O 3 was the existence of low melting eutectic and the rearrangement of grains caused by ZrO 2(m) → ZrO 2(t) transformation in the crack‐opening process zone. The effects of annealing temperature, atmosphere and indentation load on the degree of strength recovery were all related to the crack‐healing mechanisms.