TY - JOUR
T1 - Ductile-brittle transition of polycrystalline iron and iron-chromium alloys
AU - Tanaka, Masaki
AU - Wilkinson, Angus J.
AU - Roberts, Steve G.
N1 - Funding Information:
The authors gratefully acknowledge the financial support of UKAEA Culham Laboratories, and helpful discussions with Professor S.L. Dudarev.
Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2008/9/1
Y1 - 2008/9/1
N2 - Fracture toughness of polycrystalline Fe, Fe-3%Cr and Fe-9%Cr was measured by four-point bending of pre-cracked specimens at temperatures between 77 K and 150 K and strain rates between 4.46 × 10-4 and 2.23 × 10-2 s-1. For all materials, fracture behaviour changed with increasing temperature from brittle to ductile at a distinct brittle-ductile transition temperature (Tc), which increased with increasing strain rate. At low strain rates, an Arrhenius relation was found between Tc and strain rate in each material. At high strain rates, Tc was at slightly higher values than those expected from extrapolation of the Arrhenius relation from lower strain rates. This shift of Tc was associated with twinning near the crack tip. For each material, use of an Arrhenius relation for tests at strain rates at which specimens showed twinning gave the same activation energy as for the low strain rate tests. The values of activation energy for the brittle-ductile transition of polycrystalline Fe, Fe-3%Cr and Fe-9%Cr were found to be 0.21, 0.15 and 0.10 eV, respectively, indicating that the activation energy for dislocation glide decreases with increasing chromium concentration in iron.
AB - Fracture toughness of polycrystalline Fe, Fe-3%Cr and Fe-9%Cr was measured by four-point bending of pre-cracked specimens at temperatures between 77 K and 150 K and strain rates between 4.46 × 10-4 and 2.23 × 10-2 s-1. For all materials, fracture behaviour changed with increasing temperature from brittle to ductile at a distinct brittle-ductile transition temperature (Tc), which increased with increasing strain rate. At low strain rates, an Arrhenius relation was found between Tc and strain rate in each material. At high strain rates, Tc was at slightly higher values than those expected from extrapolation of the Arrhenius relation from lower strain rates. This shift of Tc was associated with twinning near the crack tip. For each material, use of an Arrhenius relation for tests at strain rates at which specimens showed twinning gave the same activation energy as for the low strain rate tests. The values of activation energy for the brittle-ductile transition of polycrystalline Fe, Fe-3%Cr and Fe-9%Cr were found to be 0.21, 0.15 and 0.10 eV, respectively, indicating that the activation energy for dislocation glide decreases with increasing chromium concentration in iron.
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U2 - 10.1016/j.jnucmat.2008.06.039
DO - 10.1016/j.jnucmat.2008.06.039
M3 - Article
AN - SCOPUS:49949111279
VL - 378
SP - 305
EP - 311
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
SN - 0022-3115
IS - 3
ER -