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Self‐inflicted fracture of expanding surface precipitates
Author(s) -
Reheman Wureguli,
Ståhle Per
Publication year - 2018
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/ffe.12872
Subject(s) - materials science , crack closure , brittleness , phase (matter) , composite material , precipitation , stress field , matrix (chemical analysis) , work (physics) , fracture (geology) , compression (physics) , stress (linguistics) , ultimate tensile strength , fracture mechanics , thermodynamics , finite element method , chemistry , linguistics , physics , philosophy , organic chemistry , meteorology
This work concerns spontaneous fracture of growing brittle precipitates in an elastic plastic matrix. The mass of the precipitate is increasing as more transformed matrix material is added to it. Under stress‐free conditions, the new phase occupies a larger volume than the original matrix material. Just outside the expanding precipitate, the matrix undergoes stretching beyond the elastic limit. The influence of the elastic plastic material behaviour is studied. A phase field model that keeps track of the phase composition is used. Both cases with a crack and without a crack are included. The growth histories from microscopic to macroscopic precipitate sizes are followed. Growth of the precipitate is very slow and quasi‐static mechanical equilibrium is assumed at all time. The result is compared with observations of hydride blisters that are formed on surfaces of zirconium alloys. The numerical model is qualified against a derived exact solution for a cylindrical precipitate without a crack. The numerical result predicts a position of the growing crack that is confirmed by the observations. Also, the predicted length of the crack is in fair agreement with the experimental observations. The depth of the blister is slightly larger than what is found at the experiments. Also, it is found that the incorporated transformed phase rejects the compression, which creates an increasing tensile stress in the inner part of the precipitate.