title: Evidence for the transition from primary to peritectic phase growth during solidification of undercooled Ni-Zr alloy levitated by electromagnetic field.
abstract: The Ni83.25Zr16.75peritectic alloy was undercooled by electromagnetic levitation method up to 198 K. The measured dendritic growth velocity shows a steep acceleration at a critical undercooling of ΔTcrit= 124 K, which provides an evidence of the transition of the primary growth mode from Ni7Zr2phase to peritectic phase Ni5Zr. This is ascertained by combining the temperature-time profile and the evolution of the solidified microstructures. Below the critical undercooling, the solidified microstructure is composed of coarse Ni7Zr2dendrites, peritectic phase Ni5Zr and eutectic structure. However, beyond the critical undercooling, only a small amount of Ni7Zr2phase appears in the solidified microstructure. The dendritic growth mechanism of Ni7Zr2phase is mainly governed by solute diffusion. While, the dendritic growth mechanism of Ni5Zr phase is mainly controlled by thermal diffusion and liquid-solid interface atomic attachment kinetics.
authors.affiliation: MOE Key Laboratory of Space Applied Physics and Chemistry, Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072, P. R. China.
authors.forename: P
authors.initials: P
authors.lastname: Lü
authors.affiliation: MOE Key Laboratory of Space Applied Physics and Chemistry, Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072, P. R. China.
authors.forename: K
authors.initials: K
authors.lastname: Zhou
authors.affiliation: MOE Key Laboratory of Space Applied Physics and Chemistry, Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072, P. R. China.
authors.forename: H P
authors.initials: HP
authors.lastname: Wang