The Role of Phase Stability in Ductile, Ordered B2 Intermetallics

Conference · Mon Jan 01 00:00:00 EST 2007

DOI:https://doi.org/10.1557/PROC-980-0980-II06-10· OSTI ID:931832

Morris, James R ^[1]; Ye, Y. Y. ^[2]; Krcmar, Maja ^[1]; Fu, Chong Long ^[1]

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1. ORNL
2. Ames Laboratory and Iowa State University

We discuss the underlying atomistic mechanism for experimentally observed large tensile ductility in various strongly ordered B2 intermetallic compounds. First-principles calculations demonstrate that all of the compounds exhibit little energy differences between the B2, B27 and B33 phases. These calculations relate observations of ductility in YAg, YCu and ZrCo to shape-memory materials including NiTi. One transformation pathway between the B2 and B33 phases establishes a connection between this phase competition, and stacking faults on the {l_brace}011{r_brace}B2 plane. The low energy of such a stacking fault will lead to splitting of the b=<100> dislocations into b/2 partials, observed in ZrCo, TiCo, and in the B19' phase of NiTi. Calculations demonstrate that this pathway is competitive with the traditional pathway for NiTi.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 931832
• Resource Relation: Journal Volume: 980; Conference: 2006 MRS Fall Meeting, Boston, MA, USA, 20061127, 20061201
• Country of Publication: United States
• Language: English