Dynamic observation of phase transformation of β-eucryptite particles in aluminum matrix composite

A composite containing both β-eucryptite particles and aluminum borate whiskers was fabricated by a squeeze casting technique. The microstructure of the composite was investigated. Interesting phenomena of β-eucryptite were observed in the composite using transmission electron microscopy (TEM). These phenomena include two steps: a degradation which results in the crystal phase of β-eucryptite turning into amorphous phase, and a further phase transformation from amorphous material to the minicrystal of LiAlO₂. The phase transformations were investigated by TEM and selected area electron diffraction pattern (SADP). The reasons for these phenomena were discussed.