Reactivity of aluminum borate whisker reinforced aluminum alloys

One of the important features of aluminum borate whisker reinforced aluminum alloy composites is the interfacial reaction which is considered to play a predominant role in strengthening mechanism and finally affects its mechanical properties. In the present study, pure Al, Mg-contained and Cu-contained alloys were selected as its matrices, Al18B4O33w/Al composites were produced by a squeeze casting method. By means of X-ray diffraction analysis, differential thermal analysis (DTA), scanning electron microscope (SEM) and transmission electron microscope (TEM) observations, the characters of the reaction between aluminum borate whisker and aluminum alloys were studied. The results show that pure Al reacts with the whisker to form Al2O3 if temperature is higher than 726.3°C. Magnesium element in aluminum alloy begins to directly affect the whisker at lower temperature of about 517.2°C. The intermediate and final products due to this reaction are Al2O3 and MgAl2O4, respectively. The present work shows that the mechanism of the interfacial reaction in a Al18B4O33W/AC8A composite is divided into two situations and chemical formulas dealt with the interfacial reaction at both low and high temperatures are proposed. However, Cu element in aluminum alloy does not take part in the chemical reaction with Al18B4O33 whisker.