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Creep Deformation and Fracture of Fibre-Reinforced Aluminum Composites

纤维增强铝复合材料的蠕变变形和断裂

基本信息

批准号：
63550527
负责人：
MATSUURA Keisuke
金额：
$ 1.34万
依托单位：
YAMAGATA University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

Creep tests were carried out an aluminum composite reinforced with continuous alumina fibres at temperatures of 573 to 773 K to examine the mechanism of high temperature deformation and fracture of composite. 1. Creep curves in the low stress range showed only almost the primary or secondary stage without reaching the tertiary stage. The creep strain was consisted of an irreversible component, possibly due to the plastic deformation of matrix around the misaligned fibres, beside a reversible component due to the elastic and inelastic deformation of matrix and fibres. 2. In the high stress range, the creep deformation proceeded by the local fracture of fibres and the plastic deformation of matrix resulting in the fracture of specimen. The creep curves showed the primary, secondary and tertiary stages. 3. The critical stress which distinguished between the low and high stress ranges was a bout 500 MPa at 573 K and 450 MPa at 773 K. The critical stress was consistent with the threshold stress which was recognized in the stress dependence of minimum creep rate. The critical stress, or the threshold stress is taken as the minimum stress for the individual cracks of fibres to propagate extensively and to cause the fracture of whole specimen.Furthermore, the effect of fibre orientation on high temperature tensile strength was examined by tensile testing the specimens which axis made the angles of Oﾟ,5ﾟ,10ﾟ,45ﾟ and 90ﾟ to fibre axis. The relation between fibre orientation and high temperature strength was well consistent with a criterion based on the maximum stress theory for fracture of composite, which was also supported by the observation of fracture surfaces.

在573 ~ 773 K温度下，对连续氧化铝纤维增强铝复合材料进行了蠕变试验，探讨了复合材料的高温变形和断裂机理。1. 在低应力范围内，蠕变曲线几乎只表现为初级或次级阶段，未达到第三阶段。蠕变应变由不可逆分量和可逆分量组成，不可逆分量可能是由基体和纤维的弹性和非弹性变形引起的，不可逆分量可能是由基体和纤维的塑性变形引起的。2. 在高应力范围内，蠕变是由纤维的局部断裂和基体的塑性变形引起试样的断裂。蠕变曲线分为初级阶段、次级阶段和第三阶段。3. 区分高低应力范围的临界应力分别为573 K时的500 MPa和773 K时的450 MPa。临界应力与阈值应力一致，这在最小蠕变速率的应力依赖性中得到了认可。取临界应力或阈值应力作为纤维单个裂纹广泛扩展并导致整个试件断裂的最小应力。通过对纤维轴与O、5、10、45、90等轴夹角的试样进行拉伸试验，考察纤维取向对高温拉伸强度的影响。纤维取向与高温强度之间的关系符合基于复合材料断裂最大应力理论的判据，这也得到了断口观察的支持。