Determination of Threshold Stress Intensity for Crack Growth at High Temperature in Silicon Carbide Ceramics
Determination of Threshold Stress Intensity for Crack Growth at High Temperature in Silicon Carbide Ceramics
复制标题
碳化硅陶瓷高温裂纹扩展阈值应力强度的测定
DOI：
10.1111/j.1151-2916.1983.tb10044.x
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发表时间：
1983
影响因子：
3.9
通讯作者：
R. E. Tressler
中科院分区：
文献类型：
--
作者：
E. Minford;R. E. Tressler
提出了一种估计裂纹扩展阈值应力强度的方法。该技术需要事先了解材料的缺陷群，并使用施加的静载荷和随后的快速断裂来评估初始施加的应力强度对缺陷行为的影响。该技术适用于非氧化气氛中 1200°C 和 1400°C 的热压碳化硅。在 1400°C 静载时间为 4 h 时，阈值应力强度确定为 ∼ 1.75 MPa·m1/2，随着初始应力强度增加到低于阈值，断裂应力略有升高的趋势。在 1200°C 静载时间 4 h 下，在低于~2.25 MPa·m1/2 的阈值应力强度下观察到明显强化。这种强化效应似乎是由裂纹尖端区域的应力松弛引起的，可能是由于涉及氧化物晶界相的塑性变形。
A method for estimating the threshold stress intensity for crack growth is presented. The technique requires prior knowledge of the flaw population of a material and uses applied static loads followed by fast fracture to assess the effect of initial applied stress intensity on flaw behavior. The technique was applied to a hot-pressed Sic at 1200° and 1400°C in a nonoxidizing atmosphere. At 1400°C with a static load time of 4 h, the threshold stress intensity was determined to be ∼ 1.75 MPa·m1/2 with a slight tendency toward higher fracture stress with increasing initial stress intensity below the threshold. At 1200°C for a static load time of 4 h, apparent strengthening was observed below a threshold stress intensity of ∼2.25 MPa·m1/2. This strengthening effect appears to result from stress relaxation in the crack-tip region, probably by plastic deformation which involves the oxide grain-boundary phase.