Crystal structure and formation mechanism of the secondary phase in Heusler Ni-Mn-Sn-Co materials

Document Type

Article

Publication Date

11-27-2014

Abstract

In the present work, crystal structure and formation mechanism of the secondary phase in Heusler Ni- Mn-Sn-Co materials were investigated using X-ray diffraction, scanning/transmission electron microscopy and selected-area electron diffraction techniques. Experimental results showed that the secondary phase presented in both Ni44.1Mn35.1Sn10.8Co10 as-cast bulk alloy and melt-spun ribbon, possessing a face-centered cubic (fcc) Ni17Sn3-type structure. The secondary phase in the as-cast bulk alloy was resulted from a eutectic reaction after the formation of a primary dendritic ? phase during cooling. However in the melt-spun rapidly solidified ribbon, the secondary phase was largely suppressed as nano-precipitates distributed along the grain boundaries, which was attributed to a divorced eutectic reaction. The secondary phase exhibited partial amorphous state due to high local coolinrate.

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