Fine Structure in Multi-Phase Zr8Ni21-Zr7Ni10-Zr2Ni7 Alloy Revealed by Transmission Electron Microscope

Abstract

The microstructure of an annealed alloy with a Zr8Ni21 composition was studied by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of three phases, Zr8Ni21, Zr2Ni7, and Zr7Ni10, was confirmed by SEM/X-ray energy dispersive spectroscopy compositional mapping and TEM electron diffraction. Distribution of the phases and their morphology can be linked to a multi-phase structure formed by a sequence of reactions: (1) L → Zr2Ni7 + L’; (2) peritectic Zr2Ni7 + L’ → Zr2Ni7 + Zr8Ni21 + L”; (3) eutectic L” → Zr8Ni21 + Zr7Ni10. The effect of annealing at 960 °C, which was intended to convert a cast structure into a single-phase Zr8Ni21 structure, was only moderate and the resulting alloy was still multi-phased. TEM and crystallographic analysis of the Zr2Ni7 phase show a high density of planar (001) defects that were explained as low-energy boundaries between rotational variants and stacking faults. The crystallographic features arise from the pseudo-hexagonal structure of Zr2Ni7. This highly defective Zr2Ni7 phase was identified as the source of the broad X-ray diffraction peaks at around 38.4° and 44.6° when a Cu-K was used as the radiation source.

Electric field gradients in Zr8Ni21 and Hf8Ni21 intermetallic compounds; results from perturbed angular correlation measurements and first-principles density functional theory

“…One additional new component is observed with a very small fraction which can be assigned to Zr 2 Ni 7 by comparing with the previous result in Zr 2 Ni 7 [11]. From SEM/X-ray EDS measurement [13] also, Zr 2 Ni 7 was found in a sample of Zr 8 Ni 21 annealed at 1233 K.…”

“…To the best of our knowledge, there is no measurement by PAC technique to characterize these materials. From previous studies [13], a pure single phase Zr 8 Ni 21 was not found to be produced by arc melting preparation. It was found [13] 21 and were confirmed by scanning electron microscopy (SEM)/X-ray energy dispersive spectroscopy (EDS) compositional mapping and transmission electron microscopy (TEM) [13].…”

“…From previous studies [13], a pure single phase Zr 8 Ni 21 was not found to be produced by arc melting preparation. It was found [13] 21 and were confirmed by scanning electron microscopy (SEM)/X-ray energy dispersive spectroscopy (EDS) compositional mapping and transmission electron microscopy (TEM) [13]. However, in the present report, we have studied both Zr 8 Ni 21 and Hf 8 Ni 21 to identify and characterize the different phases produced in these compounds.…”

“…To the best of our knowledge, there is no measurement by PAC technique to characterize these materials. From previous studies [13], a pure single phase Zr 8 Ni 21 was not found to be produced by arc melting preparation. It was found [13] that Zr 8 Ni 21 was not formed congruently from the liquid.…”

“…From previous studies [13], a pure single phase Zr 8 Ni 21 was not found to be produced by arc melting preparation. It was found [13] that Zr 8 Ni 21 was not formed congruently from the liquid. The Zr 2 Ni 7 was first solidified from the liquid and then reacted with the remaining liquid to form Zr 8 Ni 21 alloy peritectically.…”