Observation and kinetic analysis of a metastable b.c.c. phase in rapidly solidified Ni9at.%Zr and Ni8at.%Zr1at.%X alloys

Gautam Ghosh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The microstructures of rapidly solidified Ni9at.%Zr and Ni8at.%Zr1at.%X (≡ Si, Ti or Mo) alloys are found to consist predominantly of micron-sized grains having a b.c.c. (A2) structure with lattice parameter a = 0.280 ± 0.005 nm. This b.c.c. phase is metastable and undergoes decomposition into equilibrium phases α-Ni + Ni5Zr upon heating. Using relevant thermodynamic data and classical nucleation and crystal growth theory, the formation of the b.c.c. phase is rationalized in terms of kinetic hierarchy of alternative crystalline phases. We find that the calculated critical cooling rate to obtain an amorphous phase in Ni9at.%Zr alloy is about 9 × 107 K s-1 which is too high for the melt-spinning process.

Original languageEnglish (US)
Pages (from-to)277-284
Number of pages8
JournalMaterials Science and Engineering A
Volume189
Issue number1-2
DOIs
StatePublished - Dec 20 1994

ASJC Scopus subject areas

  • Materials Science(all)

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