Effect of Ni Addition on the Morphology and Microstructure of Both Conventional Cast and Melt-Spun of Al-Si-Fe-Nb (at wt%) Alloy

In this project the morphology and microstructure of both conventional cast and melt spun of Al-20Si-9Fe-1.2Nb and Al-20Si-9Fe-1.2Nb-6Ni (at wt%) alloys were investigated. Therefore, in order to study the effect of added Ni on the morphology characteristics of the above-mentioned alloy, the resulting conventional cast and ribbons of Al-20Si-9Fe-1.2Nb and Al-20Si-9Fe-1.2Nb-6Ni alloys were synthesized and analysed using OM optical microscopy, X-ray diffraction, SEM scanning electron microscopy together with EDS energy dispersive spectroscopy. Observations exhibit that, XRD patterns of Al-Si-Fe-Nb and Al-Si-Fe-Nb-Ni ribbons revealed the peaks of only alpha-Al phase. Therefore, after adding of 6 wt% Ni, peaks of alpha-Al were shifted to the relatively lower angles with a very weak intensity. Furthermore, 6 wt% Ni addition causes homogeneously scattered colonies (size range 5 -25 mu m) which contain fine spherical (primary Si and delta-Al-4(FeNiNb)Si-2 phases) particles in the alpha-Al dendrite of rapidly solidified Al-20Si-9Fe-1.2Nb alloy, the size of spherical particles were found to be in the range of 100 nm-1 mu m.