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Title: MoNbTaV Medium-Entropy Alloy

Guided by CALPHAD (Calculation of Phase Diagrams) modeling, the refractory medium-entropy alloy MoNbTaV was synthesized by vacuum arc melting under a high-purity argon atmosphere. A body-centered cubic solid solution phase was experimentally confirmed in the as-cast ingot using X-ray diffraction and scanning electron microscopy. The measured lattice parameter of the alloy (3.208 Å) obeys the rule of mixtures (ROM), but the Vickers microhardness (4.95 GPa) and the yield strength (1.5 GPa) are about 4.5 and 4.6 times those estimated from the ROM, respectively. Using a simple model on solid solution strengthening predicts a yield strength of approximately 1.5 GPa. In conclusion, thermodynamic analysis shows that the total entropy of the alloy is more than three times the configurational entropy at room temperature, and the entropy of mixing exhibits a small negative departure from ideal mixing.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [1]
  1. Taiyuan Univ. of Technology, Taiyuan (China)
  2. National Energy Technology Lab. (NETL), Albany, OR (United States); AECOM, Albany, OR (United States)
  3. National Energy Technology Lab. (NETL), Albany, OR (United States)
Publication Date:
Report Number(s):
A-CONTR-PUB-050
Journal ID: ISSN 1099-4300; ENTRFG; PII: e18050189
Grant/Contract Number:
FE0004000
Type:
Accepted Manuscript
Journal Name:
Entropy
Additional Journal Information:
Journal Volume: 18; Journal Issue: 12; Journal ID: ISSN 1099-4300
Publisher:
MDPI
Research Org:
National Energy Technology Lab. (NETL), Albany, OR (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; medium-entropy alloy; high-entropy alloy; enthalpy; entropy; lattice parameter; rule of mixture; mechanical properties; hardness; yield strength; solid solution strengthening
OSTI Identifier:
1338295