Paper number 533

ELECTRON MICROSCOPY ANALYSIS OF SQUEEZE CAST AL18B4O33W/AZ91D COMPOSITES

G. Sasaki, M. Yoshida, J. Pan and H. Fukunaga

Department of Mechanical Engineering, Hiroshima University
Kagamiyama 1-4-1, Higashi-Hiroshima, 739-8527, Japan

Summary Aluminum borate (Al18B4O33) whisker reinforced AZ91D composites fabricated by squeeze casting process have good mechanical properties at high temperature and aging effects. In as-cast composites, MgAl2O4 layer is produced at the interface between Al18B4O33 and Mg matrix with a uniform thickness of 20-30 nm. There are some preferred orientations at Al18B4O33/ MgAl2O4 and MgAl2O4/ Mg interfaces. This uniform MgAl2O4 layer prevents the direct reaction between the whisker and Mg matrix during heat-treatment under 700C. For T6 treatment, the precipitates were distributed uniformly in the matrix. Consequently, the whiskers were scarcely damaged, so that the degradation of high temperature properties is very little.
Keywords electron microscopy, aluminum borate whisker, magnesium alloy, interfacial reaction, heat stability, squeeze casting, mechanical properties.

Theme : Metal Matrix Composites ; Characterisation and Modelling

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