Stress Measurements in Polished Al-Mg Alloy and CrN Coating Using Multireflection Grazing Incidence Method

Abstract

The multi-reflection grazing incidence X-ray diffrection was used to determine residual stress gradient in the mechanically polished Al-Mg alloy and CrN coating. Also, the root mean square values of the third order lattice strain was determined using Wiliamson-Hall method. The results obtained for Al-Mg alloy show that the stress field in the surface layer as well as the microstructure (density of dislocation) depend strongly on the sample preparation. A very high residual compressive stress, which does not change significantly with depth, was measured in the CrN coating. Moreover, a large value of the measured third order strains in the coating was found.

Gradient of Residual Stress and Lattice Parameter in Mechanically Polished Tungsten Measured Using Classical X-rays and Synchrotron Radiation

“…In this work, the so-called Laplace space methodology based on AD (with Cu Kα radiation) and ED (with synchrotron radiation) techniques [22][23][24][25][26][27] was applied to measure stresses r ij and stress-free lattice parameter a 0 in the near surface layer of the mechanically polished tungsten. In this methodology, during the experiment, the information gauge is determined by exponential attenuation of the beam intensity, which can be characterized by penetration depth τ, defined in Figure 1.…”

“…Conversely, in the ED technique with white synchrotron radiation, narrow slits are applied to reduce divergence of the diffracted beam before energysensitive detector (Figure 1). The beam optics used in this work are described in References 22,23,28,and 29. The first part of experiment was performed using X-Pert PANalytical X-ray diffractometer (Cu Kα radiation) equipped with a Go¨bel mirror in the incidence beam optics. The MGIXD method, based on the AD technique, was applied to measure lattice strains at different depths close to the surface.…”

“…In the MGIXD method [21][22][23]26] (based on AD technique), the beam of X-rays falls on the sample surface at very low incident angle (α), which is held fixed during the measurement (Figure 2(a)). Consequently, X-ray beam penetrates only a shallow and constant information depth in the studied material, which can be calculated from the formula:…”

“…where: F ij ðhkl; /; wÞ are the X-ray stress factors (XSFs) [36] and / is a chosen azimuthal angle (for details see References 21,23,34,35,37,and 38).…”

“…For this study, nondestructive diffraction methods of the residual stress measurements using classical characteristic X-rays or synchrotron radiation are the most preferred. Hence, two methods, i.e., the multiple-reflection grazing incidence X-ray diffraction (MGIXD) [21][22][23] based on angular diffraction (AD) and multiple-wavelength X-ray diffraction (MMXD) [24] based on energy diffraction (ED), were applied in the present study. Such experimental techniques offer several benefits, among them the possibility to measure the depth profile of the residual stress being one of the most important ones.…”