TY - JOUR

T1 - Characterization of the gamma-loop in the Fe-P system by coupling DSC and HT-LSCM with complementary in-situ experimental techniques

AU - Bernhard, Michael Christian

AU - Fuchs, Nora

AU - Presoly, Peter

AU - Angerer, Paul

AU - Friessnegger, Bernhard

AU - Bernhard, Christian

N1 - Publisher Copyright: © 2021 The Author(s)

PY - 2021/4

Y1 - 2021/4

N2 - Solid-state phase transformations in the γ-loop of the binary Fe-P system were studied using differential scanning calorimetry (DSC) and high-temperature laser scanning confocal microscopy (HT-LSCM). In total, eight alloys with varying P content from 0.026 to 0.48 mass pct. P were investigated in the temperature range of 800 °C to 1450 °C. The first part of the present work deals with the critical evaluation of the approach to couple DSC experiments and HT-LSCM observations in order to characterize bcc/fcc phase equilibria in Fe-based γ-loops. The phase transformation temperatures of a selected alloy with 0.394%P were analyzed by DSC and HT-LSCM and compared with results of the well-established techniques of dilatometry and high-temperature X-ray diffraction (HT-XRD). Then, the overall phase boundaries of the γ-loop were reconstructed by HT-LSCM and DSC data and the phase diagram was compared with thermodynamic assessments from literature. Finally, the quantitative phase fractions of fcc and bcc at 0.394%P were analyzed by Rietveld refinement at temperatures of 1050 °C, 1100 °C and 1150 °C using in-situ HT-XRD. Although the phase boundaries of the γ-loop and phase transformation temperatures have been reproduced accurately by recently published thermodynamic optimizations, larger deviations between HT-XRD measurements and the calculations were identified for the phase fraction prediction. The present work clearly demonstrates that coupling DSC and HT-LSCM is a powerful tool to characterize γ-loops in steel for future research work.

AB - Solid-state phase transformations in the γ-loop of the binary Fe-P system were studied using differential scanning calorimetry (DSC) and high-temperature laser scanning confocal microscopy (HT-LSCM). In total, eight alloys with varying P content from 0.026 to 0.48 mass pct. P were investigated in the temperature range of 800 °C to 1450 °C. The first part of the present work deals with the critical evaluation of the approach to couple DSC experiments and HT-LSCM observations in order to characterize bcc/fcc phase equilibria in Fe-based γ-loops. The phase transformation temperatures of a selected alloy with 0.394%P were analyzed by DSC and HT-LSCM and compared with results of the well-established techniques of dilatometry and high-temperature X-ray diffraction (HT-XRD). Then, the overall phase boundaries of the γ-loop were reconstructed by HT-LSCM and DSC data and the phase diagram was compared with thermodynamic assessments from literature. Finally, the quantitative phase fractions of fcc and bcc at 0.394%P were analyzed by Rietveld refinement at temperatures of 1050 °C, 1100 °C and 1150 °C using in-situ HT-XRD. Although the phase boundaries of the γ-loop and phase transformation temperatures have been reproduced accurately by recently published thermodynamic optimizations, larger deviations between HT-XRD measurements and the calculations were identified for the phase fraction prediction. The present work clearly demonstrates that coupling DSC and HT-LSCM is a powerful tool to characterize γ-loops in steel for future research work.

KW - ?-Loop

KW - DSC

KW - Fe-P

KW - HT-LSCM

KW - HT-XRD

KW - In-situ experiments

KW - Phase diagram

KW - γ-Loop

KW - Phase diagram;

UR - http://www.scopus.com/inward/record.url?scp=85102275151&partnerID=8YFLogxK

U2 - https://doi.org/10.1016/j.matchar.2021.111030

DO - https://doi.org/10.1016/j.matchar.2021.111030

M3 - Article

VL - 174

JO - Materials characterization

JF - Materials characterization

SN - 1044-5803

IS - April

M1 - 111030

ER -