Effects of microalloying with 3d transition metals on glass formation in AlYFe alloys

The effects of microalloying on glass formation and stability were systematically investigated by substituting 0.5at.% of all 3d transition metals for Al in Al88Y7Fe5 alloys. X-ray diffraction and isothermal differential scanning calorimetry studies indicate that samples containing microadditions of Ti, V, Cr, Mn, Fe and Co were amorphous, while those alloyed with Ni and Cu were not. The onset temperatures for crystallization (devitrification) of the amorphous alloys were increased with microalloying and some showed a supercooled liquid region (ΔTx=Tx −Tg) of up to 40°C. In addition, microalloying changes the glass structure and the devitrification sequence, as determined by differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), differential thermal analysis (DTA) and high energy X-ray diffraction. The results presented here suggest that the order induced in the alloy by the transition metal microaddition decreases the atomic mobility in the glass and raises the barrier for the nucleation of α-Al, the primary devitrifying phase in most cases. New intermetallic phases also appear with microalloying and vary for different transition metal additions.