Study of crystallization mechanism of Al-based amorphous alloys by in-situ high temperature X-ray diffraction method

Abstract

The role of transition metals (TMs) addition on the formation and crystallization of amorphous Al₈₅TMs₁₀Y₅ alloys was described using in-situ high-temperature X-ray diffraction. The structural results were compared with differential scanning calorimetry and dynamical mechanical analysis to obtain detailed information about the nucleation and growth of crystalline phases. The performed analysis confirmed that Fe and Cu addition drastically changes the crystallization temperature and the phase composition of the fully crystallized alloys. While for Al₈₅Ni₁₀Y₅ alloy, the second crystallization step is related to the formation of Al₁₉Ni₅Y₃ phase, for Al₈₅(Ni, Fe)₁₀Y₅ and Al₈₅(Ni, Fe, Cu)₁₀Y₅ alloys crystallization of Al₁₅Fe₉Y₂ phase was observed. Interestingly, the performed analysis showed that forming a homogenous amorphous phase is not necessary to obtain the best corrosion resistance. It was noted that the precipitation of the YCr₂Al₂₀ phase in the Cu-rich amorphous matrix should be a much more interesting approach.