TY - JOUR

T1 - Thermodynamics of an austenitic stainless steel (AISI-348) under in situ TEM heavy ion irradiation

AU - Tunes, Matheus A.

AU - Greaves, Graeme

AU - Kremmer, Thomas

AU - Vishnyakov, Vladimir M.

AU - Edmondson, Philip D.

AU - Donnelly, Stephen E.

AU - Pogatscher, Stefan

AU - Schön, Cláudio G.

N1 - Publisher Copyright: © 2019 Acta Materialia Inc.

PY - 2019/8/27

Y1 - 2019/8/27

N2 - The stability of the face-centred cubic austenite (γ-Fe) phase in a commercial stainless steel (AISI-348) was investigated through in situ transmission electron microscopy (TEM) with heavy ion irradiation at 1073 K up to a fluence of 1.3×10 17 ions⋅cm −2 (corresponding to a dose of 46 dpa). The γ-Fe phase was observed to decompose at a fluence of around 7.8×10 15 ions⋅cm −2 (3 dpa) when a new phase nucleated and grew upon increasing irradiation dose. Scanning transmission electron microscopy (STEM) with energy dispersive X-ray (EDX) spectroscopy and multivariate statistical analysis (MVSA) were used to characterise the irradiated specimens. The combination of such experimental techniques with calculated equilibrium phase diagrams using the CALPHAD method led to the conclusion that the new phase formed upon irradiation is the body-centred cubic Cr-rich α' phase. At the nanoscale, precipitation of M 23C 6 (τ-carbide) was also observed. The results indicate that ion irradiation can assist the austenitic stainless steel to reach a non-equilibrium state similar to a calculated equilibrium state observed at lower temperatures.

AB - The stability of the face-centred cubic austenite (γ-Fe) phase in a commercial stainless steel (AISI-348) was investigated through in situ transmission electron microscopy (TEM) with heavy ion irradiation at 1073 K up to a fluence of 1.3×10 17 ions⋅cm −2 (corresponding to a dose of 46 dpa). The γ-Fe phase was observed to decompose at a fluence of around 7.8×10 15 ions⋅cm −2 (3 dpa) when a new phase nucleated and grew upon increasing irradiation dose. Scanning transmission electron microscopy (STEM) with energy dispersive X-ray (EDX) spectroscopy and multivariate statistical analysis (MVSA) were used to characterise the irradiated specimens. The combination of such experimental techniques with calculated equilibrium phase diagrams using the CALPHAD method led to the conclusion that the new phase formed upon irradiation is the body-centred cubic Cr-rich α' phase. At the nanoscale, precipitation of M 23C 6 (τ-carbide) was also observed. The results indicate that ion irradiation can assist the austenitic stainless steel to reach a non-equilibrium state similar to a calculated equilibrium state observed at lower temperatures.

UR - http://www.scopus.com/inward/record.url?scp=85071626218&partnerID=8YFLogxK

U2 - 10.1016/j.actamat.2019.08.041

DO - 10.1016/j.actamat.2019.08.041

M3 - Article

VL - 179.2019

SP - 360

EP - 371

JO - Acta Materialia

JF - Acta Materialia

SN - 1359-6454

IS - 15 October

ER -