Phase and Thermal Stability Analysis of Al-Fe-V-Si-Y Alloys After Solidification at Intermediate Cooling Rates

Abstract

Samples of RS-8009 (Al-Fe-V-Si alloy) prepared by both copper mold chill casting and rapid solidification processing were analyzed using SEM and TEM methods including CBED, selected area electron diffraction (SAD), and electron backscatter diffraction (EBSD). Diffraction analysis revealed a hexagonal phase identified as h-AlFeSi (P6/mmm a=2.45 nm c=1.25 nm) with evidence of a structural relationship to the icosahedral quasicrystalline (QC) phase and a further relationship with the α-Al-Fe-Si phase ($\operatorname{Im} \bar 3 a = 1.26 nm$), which is the desirable intermetallic in this system and also a quasicrystal approximant. The analysis confirmed the findings of earlier studies on the system, which suggested the same structural relationships using different methods. As will be shown, both phases form across a wide range of cooling rates and appear to have good thermal stabilities.