2003 Volume 44 Issue 7 Pages 1425-1428
The effect of transition metals Nb and Ta on the glass-forming ability of Ni75Si8B17 was examined. New Ni–Si–B–M (M = Nb, Ta) glassy alloys with high Ni contents above 70 at% were found to exhibit a glass transition before crystallization. The glass transition temperature (Tg) increases continuously with increasing Nb or Ta content. The supercooled liquid region (ΔTx(=Tx−Tg)) and reduced glass transition temperature (Tg⁄Tl) are 30 K and 0.59, for (Ni0.75Si0.08B0.17)96Nb4 and 35 K and 0.61, for (Ni0.75Si0.08B0.17)96Ta4, respectively. These two glassy alloys exhibit high fracture strength and good bend ductility. The maximum fracture strength of the Ni–Si–B–Nb and Ni–Si–B–Ta alloys is 2510 and 2730 MPa, respectively. All the samples can be folded through an angle of 180 degrees without fracture. The use of the glassy-type (Ni0.75Si0.08B0.17)96Ta4 alloy enabled us to form a glassy alloy rod with a diameter of 0.5 mm by the copper mold casting method. The combination of the new alloy composition, high glass-forming ability and good mechanical properties of the Ni-based glassy alloys indicates that the new bulk glassy alloy may be used as a new type of engineering material.