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This content will become publicly available on December 24, 2015

Title: Shape-memory transformations of NiTi: Minimum-energy pathways between austenite, martensites, and kinetically limited intermediate states

NiTi is the most used shape-memory alloy, nonetheless, a lack of understanding remains regarding the associated structures and transitions, including their barriers. Using a generalized solid-state nudge elastic band (GSSNEB) method implemented via density-functional theory, we detail the structural transformations in NiTi relevant to shape memory: those between body-centered orthorhombic (BCO) groundstate and a newly identified stable austenite (“glassy” B2-like) structure, including energy barriers (hysteresis) and intermediate structures (observed as a kinetically limited R-phase), and between martensite variants (BCO orientations). All results are in good agreement with available experiment. We contrast the austenite results to those from the often-assumed, but unstable B2. Furthermore, these high- and low-temperature structures and structural transformations provide much needed atomic-scale detail for transitions responsible for NiTi shape-memory effects.
 [1] ;  [2]
  1. Ames Lab., Ames, IA (United States)
  2. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0031-9007; PRLTAO
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 113; Journal Issue: 26; Journal ID: ISSN 0031-9007
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
Country of Publication:
United States