Effects of Sn addition on the glass forming ability and crystallization behavior in Ni-Zr-Ti-Si alloys

The effect of Sri substitution for Si on the glass forming ability (GFA) and crystallization behavior has been studied in Ni59Zr20Ti16Si5-xSnx (x = 0, 3, 5) alloys. A bulk amorphous Ni59Zr20Ti16Si2Sn3 alloy with diameter up to 3 mm can be fabricated by injection casting. Partial substitution of Si by Sn in Ni59Zr20Ti6Si5-xSnx alloys improves the glass forming ability. The improved GFA of the Ni59Zr20Ti16Si2Sn3 alloy is can be explained based on the lowering of liquidus temperature. The crystallization sequence becomes completely different with addition of Sri. The amorphous Ni59Zr20Ti16Si5 alloy crystallizes via precipitation of only a cubic NiTi phase in the first crystallization step, whereas the amorphous Ni59Zr20Ti16Si2Sn3 alloy crystallizes via simultaneous precipitation of orthorhombic Ni-10(Zr,Ti)(7) and cubic NiTi phases. Addition of Sri in the Ni59Zr20Ti16Si5 alloy suppresses the formation of the primary cubic NiTi phase. The bulk amorphous Ni59Zr20Ti16Si2Sn3 alloy exhibits high compressive fracture strength of about 2.7 GPa with a plastic strain of about 2%. (C) 2003 Elsevier B.V. All rights reserved.