Development of a Refractory High Entropy Superalloy (Postprint)

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Abstract:

Microstructure, phase composition and mechanical properties of a refractory high entropy super alloy, AlMosub 0.5NbTasub 0.5TiZr, are reported in this work. The alloy consists of a nano-scale mixture of two phases produced by the decomposition from a high temperature body-centered cubic BCC phase. The first phase is present in the form of cuboidal-shaped nano-precipitates aligned in rows along 100-type directions, has a disordered BCC crystal structure with the lattice parameter asub 1 326.9 plus or minus 0.5 pm and is rich in Mo, Nb and Ta. The second phase is present in the form of channels between the cuboidal nano-precipitates, has an ordered B2 crystal structure with the lattice parameter asub 2 330.4 plus or minus 0.5 pm and is rich in Al, Ti and Zr. Both phases are coherent and have the same crystallographic orientation within the former grains. The formation of this modulated nano-phase structure is discussed in the framework of nucleation-and-growth and spinodal decomposition mechanisms. The yield strength of this refractory high entropy super alloy is superior to the yield strength of Ni-based super alloys in the temperature range of 20 degrees C to 1200 degrees C.

Author(s):
Senkov, Oleg N. ; Isheim, Dieter ; Seidman, David N. ; Pilchak, Adam L.
Author Organization(s):
AFRL Materials and Manufacturing Directorate Wright Patterson Air Force Base United States
Descriptive Note:
Journal Article
Supplementary Note:
Entropy , 18, 3, 01 Jan 0001, 01 Jan 0001, This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
Pagination:
0015

Security Markings

DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release
Distribution Statement:
Approved For Public Release;

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
AFRL-RX-WP-JA-2017-0110
Contract/Grant Number(s):
FA8650-15-D-5230
Monitor Series:
AFRL-RX-WP-JA-2017-0110
 Subject Terms
Joint Capability Areas:
JCA_5_Command and Control; JCA_5.3_Planning; JCA_1.2.3_Educating; JCA_1.2.6_Concepts
Communities of Interest:
Advanced Electronics
Descriptor(s):
mechanical properties, SUPERALLOYS, MICROSTRUCTURE, REFRACTORY MATERIALS, crystal structure, materials science, phase transformations, diffraction, grain boundaries, electron microscopy
Field(s)/Group(s):
Metallurgy and Metallography
Keyword(s):
10011
Report Date:
2016 Mar 17
Creation Date:
2017 Jun 12