Yuanchang Shi

Microstructural evolution in amorphous Al-based alloys

The Al90Fe5Ce5 and Al83Zn10Ce7 alloys were analysed with the aim of studying the microstructural evolution under various processing conditions. In addition to the icosahedral phase surrounded by the Al phase, the fine scale distribution of the metastable Al6Fe phase produces on annealing the amorphous Al90Fe5Ce5 alloy. In Al83Zn10Ce7 alloy, the stable intermetallic compound Al2ZnCe2 forms as the primary phase during solidification. The precipitation nanocrystals of Al were accompanied with the intermetallic compound Al2ZnCe2. For the amorphous Al-based alloys, the high glass formation appears to be controlled largely by the suppression of growth of nuclei formed during rapid melt quenching. The competitive nucleation and growth limitation of the various phases are attributed to the complex microstructures characteristic of the Al-based alloys.

Precipitation of an icosahedral phase in amorphous Al90Fe5Ce5 alloy

Isothermal and non-isothermal differential scanning calorimetry experiments were carried out to study rapidly solidified Al90Fe5Ce5 alloy. Microstructural analysis suggests that icosahedral nanoparticles are homogeneously distributed in the matrix of annealed amorphous Al90Fe5Ce5 alloy. The presence and homogeneous distribution of icosahedral structure units and icosahedral short-range domains appear to be critical for the formation and stability of the amorphous phase.