Nucleation and growth in undercooled melts of bulk-metallic-glass forming Zr ₆₀ Ni ₂₅ Al ₁₅ alloy

A livitation method using alternating and static magnetic fields was used to measure nucleation and growth of the crystalline phases in melts of the bulk-metallic-glass forming Zr ₅₀ Ni ₂₅ Al ₁₅ alloy. For comparison, Zr _66.7 Ni _33.3 and Zr _66.5 Ni _33.2 Al _0.3 were also examined. Nucleation undercooling in the bulk-metallic-glass forming Zr ₆₀ Ni ₂₅ Al ₁₅ alloy did not depend on the cooling rate (<10 ² K/s), and the maximum undercooling observed was approximately 200K. Recalescence was not observed in the cooling curves of the Zr ₆₀ Ni ₂₅ Al ₁₅ and the Zr _66.5 Ni _33.2 Al _0.3 alloys. The growth velocity of the crystalline phase in the Zr ₆₀ Ni ₂₅ Al ₁₅ alloy was of the order of 10 ^-4 m/s even at a undercooling of 100 K. In contrast, clear recalescence was always observed in the Zr _66.7 Ni _33.3 alloy. The results showed that the addition of Al into the Zr-Ni alloy significantly reduced growth velocity of the crystalline phases. The extremely low growth rate in the Zr-Ni-Al system can contribute to the high glass forming ability.