FRACTURE-TOUGHNESS ANISOTROPY AND TOUGHENING MECHANISMS OF A HOT-PRESSED ALUMINA REINFORCED WITH SILICON-CARBIDE WHISKERS
FRACTURE-TOUGHNESS ANISOTROPY AND TOUGHENING MECHANISMS OF A HOT-PRESSED ALUMINA REINFORCED WITH SILICON-CARBIDE WHISKERS
复制标题
DOI：
10.1111/j.1151-2916.1993.tb05304.x
复制
发表时间：
1993-04-01
影响因子：
3.9
通讯作者：
WASEN, J
中科院分区：
文献类型：
--
作者：
HANSSON, T;WARREN, R;WASEN, J
用四点弯曲法测定了热压氧化铝和含33vol%SiC晶须的热压氧化铝/SiC晶须复合材料的断裂韧性。“检查了两批复合材料，其中一批比另一批显示出更大程度的晶须聚集。氧化铝的断裂韧性约为4 MN.m-3/2，而复合材料的断裂韧性在5和8 MN.m-3/2之间变化，取决于微观结构的均匀性和裂纹扩展方向。裂纹偏转结合从沿晶断裂到穿晶断裂的变化被提出作为SiC晶须增强氧化铝的上级断裂韧性的解释，与未增强氧化铝相比。复合材料的断裂韧性与裂纹扩展方向在相同的裂纹平面的变化。对于晶须分布均匀的复合材料，这种效应可以用裂纹偏转来描述，具有很好的精度。然而，在晶须聚集的材料中，断裂韧性随裂纹扩展方向的变化较大，不能完全用裂纹偏转来解释。
The fracture toughness of a hot-pressed alumina and that of a hot-pressed alumina/SiC-whisker composite containing 33 vol% SiC whiskers were measured by four-point bending on single-edge precracked bend bars having sharp precracks created by ''bridge indentation.'' Two batches of the composite were examined, one exhibiting a greater degree of whisker clustering than the other. The fracture toughness of the alumina was around 4 MN.m-3/2 whereas that of the composite varied between 5 and 8 MN.m-3/2 depending on microstructural uniformity and crack-propagation direction. Crack deflection in combination with a change in fracture from intergranular to transgranular fracture is proposed as an explanation of the superior fracture toughness of SiC-whisker-reinforced alumina as compared to unreinforced alumina. The composite exhibited a variation in fracture toughness with the crack-propagation direction in identical crack planes. This effect could with good accuracy be described in terms of crack deflection for the composite with uniform whisker distribution. However, in the material with whisker clustering the variation of the fracture toughness with crack-growth direction was greater and could not entirely be explained by crack deflection.