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Stability maps to predict anomalous ductility in B2 materials
Physical Review B
  • Ruoshi Sun, University of Illinois at Urbana-Champaign
  • Duane D. Johnson, Iowa State University
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While most B2 materials are brittle, a new class of B2 (rare-earth) intermetallic compounds is observed to have large ductility. We analytically derive a necessary condition for ductility (dislocation motion) involving ⟨111⟩ versus ⟨001⟩ slip and the relative stability of various planar defects that must form. We present a sufficient condition for antiphase boundary bistability on {11¯0} and {112¯} planes that allows multiple slip systems. From these energy-based criteria, we construct two stability maps for B2 ductility that use only dimensionless ratios of elastic constants and defect energies, calculated via density functional theory. These two conditions fully explain and predict enhanced ductility (or lack thereof) for B2 systems. In the 23 systems studied, the ductility of YAg, ScAg, ScAu, and ScPd, ductile-to-brittle crossover for other rare-earth B2 compounds, and brittleness of all classic B2 alloys and ionic compounds are correctly predicted.


This article is from Phys. Rev. B 87, 104107 (2013), doi:10.1103/PhysRevB.87.104107. Posted with permission.

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American Physical Society
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Ruoshi Sun and Duane D. Johnson. "Stability maps to predict anomalous ductility in B2 materials" Physical Review B Vol. 87 Iss. 10 (2013) p. 104107
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