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Preparation and Reactivity of Gasless Nanostructured Energetic Materials
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Solidification of Ni-Re Peritectic Alloys
W J Boettinger1, D E Newbury2, N W M Ritchie2
1Theiss Research, La Jolla, CA 92037.
Metallurgical and Materials Transactions. A. Physical Metallurgy and Materials Science
|October 16, 2020
Summary
This study clarifies the Nickel-Rhenium (Ni-Re) phase diagram by precisely determining the peritectic invariant temperature and phase compositions using differential thermal analysis and microstructural analysis. Findings resolve previous discrepancies in Ni-Re alloy phase behavior.
Area of Science:
- Materials Science
- Metallurgy
- Physical Chemistry
Background:
- Nickel-Rhenium (Ni-Re) alloys are critical in high-temperature applications.
- Existing Ni-Re phase diagrams show discrepancies, necessitating accurate thermodynamic and phase boundary data.
Purpose of the Study:
- To resolve conflicting data in previously published Ni-Re phase diagrams.
- To accurately determine the peritectic invariant and phase compositions in Ni-Re alloys.
- To analyze microsegregation and solidification behavior in as-cast Ni-Re alloys.
Main Methods:
- Differential Thermal Analysis (DTA) for thermal events.
- Microstructural analysis to examine phase distribution.
- Microprobe measurements for elemental composition analysis.
Main Results:
- The peritectic invariant (L + HCP → FCC) was determined at 1561.1 ± 3.4 °C.
- Compositions of liquid, FCC, and HCP phases at the peritectic invariant were precisely quantified.
- A partition coefficient (k) of 1.54 ± 0.09 was calculated for solidification, with minor deviations from Scheil behavior observed.
Conclusions:
- This investigation provides a refined Ni-Re phase diagram, resolving prior inconsistencies.
- The determined peritectic invariant and phase compositions are crucial for alloy design.
- Microsegregation analysis offers insights into solidification kinetics in Ni-Re systems.
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