共晶体系
材料科学
微观结构
金属间化合物
枝晶(数学)
冶金
铝
铸造
疲劳极限
粒径
复合材料
粒子(生态学)
合金
化学工程
几何学
数学
海洋学
工程类
地质学
作者
Q.G Wang,Diran Apelian,Diana A. Lados
出处
期刊:Journal of Light Metals
[Elsevier]
日期:2001-02-01
卷期号:1 (1): 85-97
被引量:247
标识
DOI:10.1016/s1471-5317(00)00009-2
摘要
A quantitative study of the interactions between microstructural features such as secondary dendrite arm spacing (SDAS), eutectic structure, matrix strength, and fatigue behavior of two Al–7% Si–Mg casting alloys with magnesium contents of 0.4% and 0.7%, respectively, has been conducted. In the absence of casting defects, the influence of microstructural features on the fatigue performance becomes more pronounced. The degree and rate of microdamage (microcracking) is strongly affected by the strength of the matrix, and especially by the eutectic particle size, morphology, and distribution (clustering). A soft matrix (under-aged alloys) will generate more local microdamage compared to a peak-aged one. Large and elongated eutectic particles present in unmodified alloys result in lower fatigue lives. A decrease of fatigue life with increasing Mg and Fe content is observed, mainly due to the increased sizes of Fe-rich intermetallic particles. Microstructures with similar eutectic particle size and morphology as the Sr-modified ones, show a minimum fatigue life at intermediate SDAS values (∼60 μm), which is related to the continuity of particles on the dendrite cell boundaries. For coarser microstructures (SDAS>60μm), the increase in fatigue life is attributed to the reduced damage rate along the cell boundaries.
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