(95-0308)A Study of Estimating Cu Diffusion Coefficient in Fe by Monte Carlo Simulation

摘要

The Cu precipitate formed in reactor pressure vessels (RPV) by irradiation is one of the main originfor embrittlement. To understand the mechanism of the embrittlement, revelation of irradiation effectson the Cu diffusion is important. For Cu diffusion, the Cu diffusion coefficient (D) is the main parameter.We have reported that, by measuring the concentration profile of Cu in diffusion couples using atomprobe tomography (APT), D was estimated directly (shown in Fig 1 as Dt1). However, as temperaturedecreases, the concentration profile of Cu in Fe becomes difficult to measure because that the solubilityof Cu in Fe decreases with temperature decreasing. Therefore, Fe-Cu alloys were employed. Bymeasuring Cu precipitate size, number density and Cu concentration in alloys using APT, the D wasestimated by a mode that simplified precipitation kinetics [1] (shown in Fig 1 as D_(t2)). We can see Dt2was larger than Dt1. In this study, we employ Monte Carlo simulation to estimate D in Fe-Cu alloys andexpect to explain why the D estimated by two methods show the different values.