Formation, thermal stability and mechanical properties of new amorphous Al89Fe10Zr1 alloy

A new amorphous alloy with high tensile strength and good bending ductility was fabricated from a melt-spun Al89Fe10Zr1 alloy without the lanthanide (Ln) element. The Al content for glass formation is believed to be the highest in the Ln-free Al-based alloys. The as-quenched phase changes to a mixed structure of amorphous and fcc-Al phases with decreasing Fe content to 7-9 at%, and the particle size of the Al phase is 40 nm at 7%Fe, 10 nm at 8%Fe and 5 nm at 9%Fe. The mixed phase alloys also have good bending ductility. The tensile fracture strength (sigma(f)) is 1050 MPa for the amorphous Al89Fe10Zr1 alloy and decreases to 720-1000 MPa for the mixed phase alloys with 7 to 9%Fe concentrations. The amorphous alloy crystallizes by two-stage reactions of Am --> Am + Al --> Al + Al3Zr + Al13Fe4 and the onset temperature of each exothermic reaction is 460 and 650 K. The sigma(f) of the amorphous alloy increases to 1220 MPa without detriment to good ductile nature by the precipitation of about 20 vol% Al phase. The achievement of high sigma(f) combined with good bending ductility in the Ln-free Al-Fe-Zr alloys with the high Al concentration of about 90% is important as a new basic alloy system to produce a high-strength Al-based alloy with low specific weight and inexpensiveness.