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

The effect of Sn substitution for Si on the glass forming ability (GFA) and crystallization behavior has been studied in Ni₅₉Zr ₂₀Ti₁₆Si_{5 - x}Sn_x (x = 0, 3, 5) alloys. A bulk amorphous Ni₅₉Zr₂₀Ti₁₆Si ₂Sn₃ alloy with diameter up to 3 mm can be fabricated by injection casting. Partial substitution of Si by Sn in Ni₅₉Zr ₂₀Ti₆Si_{5 - x}Sn_x alloys improves the glass forming ability. The improved GFA of the Ni₅₉Zr ₂₀Ti₁₆Si₂Sn₃ alloy is can be explained based on the lowering of liquidus temperature. The crystallization sequence becomes completely different with addition of Sn. The amorphous Ni ₅₉Zr₂₀Ti₁₆Si₅ alloy crystallizes via precipitation of only a cubic NiTi phase in the first crystallization step, whereas the amorphous Ni₅₉Zr₂₀Ti₁₆Si ₂Sn₃ alloy crystallizes via simultaneous precipitation of orthorhombic Ni₁₀(Zr,Ti)₇ and cubic NiTi phases. Addition of Sn 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%.