Stress distribution in depth of NiCr + Cr2O3 systems using high-energy synchrotron X-rays in transmission mode

[摘要] NiCr alloys develop chromia layers in oxidizing high temperature environments. The stress in oxide layer was largely explored, whereas too few works were devoted to the stress distribution in the underlying metallic substrate. To determine the stress distribution in a duplex oxide-metallic substrate system, a variant of sin(2)psi method in transmission mode using high-energy synchrotron X-rays has been developed. 103.4 keV synchrotron X-rays have been used to penetrate 6 x 6 x 0.4 mm and empty set6 x 0.9 mm samples with different oxidation conditions. In order to obtain the stress gradient from the top surface to the bottom surface, the patterns of diffraction were collected and then were analyzed by a complete data processing. The stress varies towards the surface in a non-linear manner, especially near the interface zone. In order to better understand the stress distribution of such a duplex oxide-metallic substrate system, the stress caused by chromium diffusion is investigated by proposing numerical values for coupling coefficient, which finally can partially explain the stress variation near the interface zone. (C) 2021 Elsevier B.V. All rights reserved.

[发布日期] 2021-09-15

[关键词] High-energy synchrotron X-rays;Transmission mode;Chromium diffusion;Stress distribution;Oxidation of chromium alloys;Chromium concentration profiles