Abstract: Quality 9Al_2O_3-2B_2O_3 whisker reinforced 6061Al or Al composites have been prepared by technique of squeeze casting.The mechanical properties of the 9Al_2O_3·2B_2O_3(w)/6061Al composites could be hardly improved by T6 treatment,owing to cause the remarkable interracial reaction.An observation under high resolution trans- mission electron microscope on interfaces shows that the serious chemical reaction occurs and the product is Al_2MgO_4.But no such reaction is found at the interfaces of 9Al_2O_3. 2B_2O_3(w)/Al composite.EDS analysis on the interfaces shows that above mentioned interracial reaction may be resulted from the interracial segregation of Mg atoms in 6061Al matrix during sequeeze casting.

Key words: aluminium borate whisker, Al matrix composite, strength, interracial structure