Molecular dynamics simulation of Cr-precipitate demixing in FeCr alloys

TY - JOUR

T1 - Molecular dynamics simulation of Cr-precipitate demixing in FeCr alloys

AU - Grammatikopoulos, Panagiotis

AU - Nordlund, Kai

N1 - Funding Information: The work has been performed under the HPC-EUROPA2 project (project number: 228398) with the support of the European Commission - Capacities Area - Research Infrastructures. The authors would like to thank Dr Konstantina Mergia for her support, and acknowledge CSC – IT Center for Science Ltd. for the allocation of computational resources.

PY - 2014/7/3

Y1 - 2014/7/3

N2 - The mechanical properties of FeCr alloys rely heavily on atomic distribution and can be affected by phenomena such as Cr precipitation. While precipitation of FeCr alloys of various Cr concentrations has been studied before, dissolution of already existing Cr precipitates in FeCr alloys has not; this was the focus of this study. Our means of investigation was molecular dynamics computer simulation: we set up a number of configurations of FeCr alloys containing Cr precipitates of various sizes embedded in matrices of either pure Fe or with a 15% random Cr distribution, and examined their behaviour after thermal ageing at temperatures T ranging between 600 and 2000 K. The T range was selected so that it would include the (+′)- transition in the standard FeCr phase diagram. High-T results provide insight into the mechanisms that govern the dissolution: Cr precipitates dissolve by vacancy exchange, leading to a random distribution of Cr atoms in an Fe matrix, as the short-range order parameter shifts from a positive value (clustering) to zero (random atomic arrangement). Precipitates at low T were found to be stable, as were those at intermediate T (∼1000 K), in agreement with previous experimental and simulation studies that challenge the standard phase diagram's reliability.

AB - The mechanical properties of FeCr alloys rely heavily on atomic distribution and can be affected by phenomena such as Cr precipitation. While precipitation of FeCr alloys of various Cr concentrations has been studied before, dissolution of already existing Cr precipitates in FeCr alloys has not; this was the focus of this study. Our means of investigation was molecular dynamics computer simulation: we set up a number of configurations of FeCr alloys containing Cr precipitates of various sizes embedded in matrices of either pure Fe or with a 15% random Cr distribution, and examined their behaviour after thermal ageing at temperatures T ranging between 600 and 2000 K. The T range was selected so that it would include the (+′)- transition in the standard FeCr phase diagram. High-T results provide insight into the mechanisms that govern the dissolution: Cr precipitates dissolve by vacancy exchange, leading to a random distribution of Cr atoms in an Fe matrix, as the short-range order parameter shifts from a positive value (clustering) to zero (random atomic arrangement). Precipitates at low T were found to be stable, as were those at intermediate T (∼1000 K), in agreement with previous experimental and simulation studies that challenge the standard phase diagram's reliability.

KW - FeCr alloys

KW - dissolution

KW - miscibility gap

KW - molecular dynamics

UR - http://www.scopus.com/inward/record.url?scp=84904857824&partnerID=8YFLogxK

U2 - 10.1080/10420150.2014.920020

DO - 10.1080/10420150.2014.920020

M3 - 文章

AN - SCOPUS:84904857824

SN - 1042-0150

VL - 169

SP - 646

EP - 654

JO - Radiation Effects and Defects in Solids

JF - Radiation Effects and Defects in Solids

IS - 7

ER -