Effect of Nb addition on the glass forming ability and mechanical properties in the Ni-Zr-Al-Hf-Nb alloys

The effect of substituting Nb for Zr on the glass forming ability (GFA) and mechanical properties of Ni60Zr27−xAl6Hf7Nbx (x = 0 – 14) alloys was investigated. The substitution of Zr with Nb of 0 – 14 at% improved the GFA. When increasing the Nb content x from 0 – 14, the glass transition temperature, Tg , and the crystallization temperature, Tx, of melt-spun Ni60Zr27−xAl6Hf7Nbx (x = 0 – 14) alloys increased from 833 and 863 K to 877 and 914 K, respectively. The Ni60Zr27−xAl6Hf7Nbx (x = 8, 10, 12 and 14) alloys exhibited high Trg (= Tg/Tm liq) (>0.615), γ (= Tx/Tg +Tliq m )(>0.4) values and a wide supercooled liquid region, Tx (= Tx – Tg) (>36 K) enabling the fabrication of bulk metallic glass (BMG) with a diameter above 1 mm. As such, Ni60Zr17Al6Hf7Nb10 and Ni60Zr15Al6Hf7Nb12 alloys with a maximum diameter of 2 mm could be fabricated by injection casting. These bulk amorphous alloys also exhibited good mechanical properties, where the true ultimate compressive strength, strain and Vickers hardness (Hv) were approximately 3.0 GPa, 2.08% and 713, respectively, for the amorphous Ni60Zr17Al6Hf7Nb10 alloy, and 3.1 GPa, 2.22% and 687, respectively, for the amorphous Ni60Zr15Al6Hf7Nb12 alloy. C 2006 Springer Science + Business Media, Inc.