Bulk synthesis by spray forming of Al-Cu-Fe and Al-Cu-Fe-Sn alloys containing a quasicrystalline phase

In this study, Al-Cu-Fe alloys without and with the addition of Sn and containing a quasicrystalline phase were spray deposited. The spray-deposited bulk materials were characterized in terms of microstructure and hardness. The results showed that the Al62.5Cu25Fe12.5 alloy contains the icosahedral quasicrystalline phase (i-phase) along with the minor λ-Al13Fe4 phase, whereas the Al62.5Cu25Fe12.5 + Sn alloy contains five phases: the major i-phase and the crystalline phases of Sn, θ-Al2Cu, λ-Al13Fe4 and β-AlFe(Cu) phases. These results have been corroborated by X-ray diffraction (XRD), scanning and transmission electron microscopies (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 and then decreased steadily with increase in the applied load, while that for Al-Cu-Fe-Sn alloy it was originally somewhat lower, then decreased dramatically with slight increase in the applied load but stayed constant with further load increase. The hardness indentations in Al-Cu-Fe alloy introduced cracking in the material, whereas in the case of Al-Cu-Fe-Sn alloy the Sn-rich areas inhibited the crack growth. The present study provides an insight into the mechanism of phase and microstructural evolutions during spray forming of the studied alloys. Furthermore, the role of Sn in terms of microstructure and properties is highlighted.