The Al(L)+AIB12 <-> AIB(2) peritectic transformation and its role in the formation of high aspect ratio AIB(2) flakes

A new family of metal matrix composites (MMCs) based on high aspect ratio A lB2 is being developed, Preparation of these MMCs involves the conversion o f low aspect ratio AlB2 to high aspect ratio AlB2. This conversion is assoc iated with the Al-(L) + AlB12 <-> AlB2 peritectic transformation. There is confusion surrounding the temperature at which this transformation occurs. Its value has been reported as high as 1500 degrees C and as low as 980 C, In this paper, the peritectic temperature has been Investigated using calor imetric methods and determined to be 956 +/- 5 degrees C. In addition, an u nexpected conversion of low aspect ratio AlB2 to high aspect ratio AlB2 has been identified near the peritectic temperature.