Development of bulk quasicrystalline materials by spray forming

Abstract

In this study, Al-Cu-Fe based stable quasicrystalline alloys were spray deposited in bulk (around 40 kg), with and without addition of Sn. The spray deposited materials were characterized in terms of microstructure, hardness and thermal stability. The results showed that the Al 62.5 Cu 25 Fe 12.5 alloy contains the single quasicrystalline icosahedral phase (i-phase) along with a minor λ-Al 13 Fe 4 phase, whereas the Al 62.5 Cu 25 Fe 12.5 +Sn alloy contains five phas- es: the major i-phase, β-Sn, θ-Al 2 Cu, λ-Al 13 Fe 4 and β-AlFe(Cu) phases. These results have been corroborated by X-ray diffraction (XRD), scanning and transmission electron micros- copy (SEM and TEM) and differential scanning calorimetry (DSC). The hardness value of the Al-Cu-Fe alloy reached 10.5 GPa at 50 g load, while that for Al-Cu-Fe-Sn alloy was some- what lower. DSC analysis showed only one transformation peak at 885.5 o C for i-phase in Al 62.5 Cu 25 Fe 12.5 , indicating the melting temperature. The present study provides an insight into the mechanism of phase and microstructural evolutions during spray forming of the studied alloys. The role of Sn in terms of microstructure and properties is highlighted.