The Al(L)+AIB12 ⇆ AIB2 peritectic transformation and its role in the formation of high aspect ratio AIB2 flakes

A new family of metal matrix composites (MMCs) based on high aspect ratio AlB2 is being developed, Preparation of these MMCs involves the conversion of low aspect ratio AlB2 to high aspect ratio AlB2. This conversion is associated 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 calorimetric methods and determined to be 956 +/- 5 degrees C. In addition, an unexpected conversion of low aspect ratio AlB2 to high aspect ratio AlB2 has been identified near the peritectic temperature.