Heterogeneous nucleation mechanism in Al-Fe-Si amorphous alloys

Al 70 Fe 13 Si 17 alloys were melt-spun with commercial grain refiner additions containing TiB 2 and Al 3 Ti particles. X-ray diffraction. calorimetry and transmission electron microscopy revealed incomplete vitrification. The size and number density of Al crystals increased with decreasing quench rate. Full crystallisation led to formation of β-Al 9 FeSi 2 and Al. In as-quenched samples nucleation events on TiB 2 particles were surrounded by nanocrystalline α-Al particles embedded in amorphous phase. Boride particles were covered in a thin Ti-containing layer and surrounded by a featureless zone reminiscent of a peritectic reaction and they exhibited an orientation relationship to next neighbour Al particles.