Hertzian flaw analysis and models for the prediction of flexural fracture strength of Al2O3 and Al2O3/SiCp nanocomposites

被引:4
作者
Anya, CC [1 ]
机构
[1] Univ Oxford, Dept Mat, Oxford OX1 3PH, England
关键词
D O I
10.1023/A:1004311811808
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
A study is presented comparing the statistics of observed crack-originating flaws on fracture surfaces of samples of Al2O3 and its composites (having 5 and 15 vol % SiC particle, SiCp) with those determined by the Hertzian indentation analysis. Cracks originating from Vickers microindents are also examined using transmission electron microscopy (TEM). Critical flaws determined by the Hertzian analysis predict experimental fracture strengths reasonably well when Orowan's model of obtaining the latter is used. This model is supported by microstructural features, which strongly suggest blunt crack-tips. The critical flaw sizes of alumina and the 5 vol % SiCp composite are found to be practically the same. Hence the explanation of the higher strength of the composites (relative to alumina) based on flaw size is improbable. The composite with 15 vol % SiCp is tougher and has a lower fracture strength in comparison with those of the 5 vol % SiCp composite. Therefore an increase in toughness does not satisfactorily explain the strengthening trend. The change in the mode of fracture and the interspacing distances (implicitly the heights) of the fracture steps are suggested as the main factors that control strengthening in these materials. (C) 1998 Chapman & Hall.
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页码:977 / 984
页数:8
相关论文
共 19 条
[1]   Indentation fracture toughness and surface flaw analysis of sintered alumina/SiC nanocomposites [J].
Anya, CC ;
Roberts, SG .
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 1996, 16 (10) :1107-1114
[2]   Pressureless sintering and elastic constants of Al2O3-SiC 'nanocomposites' [J].
Anya, CC ;
Roberts, SG .
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 1997, 17 (04) :565-573
[3]  
ANYA CC, IN PRESS ACTA MAT
[4]   PROCESSING AND PROPERTIES OF AL2O3/SIC NANOCOMPOSITES [J].
BORSA, CE ;
JIAO, S ;
TODD, RI ;
BROOK, RJ .
JOURNAL OF MICROSCOPY-OXFORD, 1995, 177 :305-312
[5]  
Davidge R.W., 1986, MECH BEHAV CERAMICS, P31
[6]   PROPAGATION OF CLEAVAGE CRACKS IN CRYSTALS [J].
GILMAN, JJ .
JOURNAL OF APPLIED PHYSICS, 1956, 27 (11) :1262-1269
[8]   EFFECT OF INDENTER ELASTICITY ON HERTZIAN FRACTURE OF BRITTLE MATERIALS [J].
JOHNSON, KL ;
OCONNOR, JJ ;
WOODWARD, AC .
PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL AND PHYSICAL SCIENCES, 1973, 334 (1596) :95-117
[9]   INTERACTION BETWEEN A CRACK FRONT AND CLEAVAGE STEPS [J].
LANGE, FF ;
LAMBE, KAD .
PHILOSOPHICAL MAGAZINE, 1968, 18 (151) :129-&
[10]   ATOMICALLY SHARP CRACKS IN BRITTLE SOLIDS - AN ELECTRON-MICROSCOPY STUDY [J].
LAWN, BR ;
HOCKEY, BJ ;
WIEDERHORN, SM .
JOURNAL OF MATERIALS SCIENCE, 1980, 15 (05) :1207-1223