skip to main content

DOE PAGESDOE PAGES

This content will become publicly available on April 19, 2017

Title: Misoriented grain boundaries vicinal to the (111) <11¯0> twin in nickel part II: Thermodynamics of hydrogen segregation

Grain boundary engineered materials are of immense interest for their resistance to hydrogen embrittlement. This work builds on the work undertaken in Part I on the thermodynamic stability and structure of misoriented grain boundaries vicinal to the Σ3 (111) <11¯0> (coherent-twin) boundary to examine hydrogen segregation to those boundaries. The segregation of hydrogen reflects the asymmetry of the boundary structure with the sense of rotation of the grains about the coherent-twin boundary, and the temperature-dependent structural transition present in one sense of misorientation. This work also finds that the presence of hydrogen affects a change in structure of the boundaries with increasing concentration. The structural change effects only one sense of misorientation and results in the reduction in length of the emitted stacking faults. Moreover, the structural change results in the generation of occupied sites populated by more strongly bound hydrogen. The improved understanding of misoriented twin grain boundary structure and the effect on hydrogen segregation resulting from this work is relevant to higher length-scale models. To that end, we examine commonly used metrics such as free volume and atomic stress at the boundary. In conclusion, free volume is found not to be useful as a surrogate for predicting themore » degree of hydrogen segregation, whereas the volumetric virial stress reliably predicts the locations of hydrogen segregation and exclusion at concentrations below saturation or the point where structural changes are induced by increasing hydrogen concentration.« less
Authors:
 [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
OSTI Identifier:
1263646
Report Number(s):
SAND--2016-3147J
Journal ID: ISSN 1478-6435; 644873
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Philosophical Magazine (2003, Print)
Additional Journal Information:
Journal Name: Philosophical Magazine (2003, Print); Journal Volume: 96; Journal Issue: 14; Journal ID: ISSN 1478-6435
Publisher:
Taylor & Francis
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE misorientation; twins; grain boundaries; nickel; hydrogen in metals; interfacial segregation; grain boundary engineering; hydrogen embrittlement