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.