Morphology of Order-Disorder Structures in Rapidly Solidified L12 Intermetallics

Abstract

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Order-disorder morphologies in rapidly solidified ε/ε′-Ni5Ge3 intermetallic

“…Consequently, we conclude that the contrast revealed by etching is due to incomplete chemical ordering, with the etchant preferentially attacking the disordered material while leaving the ordered material intact. Similar behaviour has been observed in other Ni-Ge alloys [11,12]. In order to determine whether ordering occurs in the solid-state or upon solidification at the liquidus temperature differential scanning calorimetry (DSC) was performed on powders from the 150 -106 µm size fraction, the results of which are given in Figure 4a.…”

Presence of έ and ε crystal structures in rapidly solidified intermetallic compound Ni5Ge3

“…In this case, the etchant affects the disordered material and leaves intact the ordered material. Similar behaviour also has been observed in the compound Ni3Ge [16,17] and is consistent with the known chemical resistance of ordered imtermetallic compounds. Ni5Ge3 is a congruently melting compound with a homogeneity range of 34.6 -44.5 at.…”

Mechanical Properties of Rapidly Solidified Ni5Ge3 Intermetallic

“…An EDX line scan perpendicular to a plate & lath is showed in Figure 2 (b). This shows that the material is chemically homogeneous and that the contrast is therefore not the result of compositional difference between the plate & lath and the surrounding matrix, as might arise from solute partitioning during solidification [11,12]. We conclude therefore that the contrast revealed by etching does not indicate any relation to phase difference (XRD) nor chemical composition (EDX).…”