Anisotropy of the acoustic emission signal on scratch testing of a single crystal of aluminum
Year: 2019
Type: article
Abstract: In modern materials science, one of the main directions of solving the problem of improving the performance of parts and mechanisms is a radical improvement in the properties of material surface through its modification or application of coatings. To control the mechanical properties of structurally modified layers and coatings, local test methods are becoming increasingly common. Indentation and scratch testing are the most popular among such local techniques. To increase the significance of these tests, it is plausible to combine them with the registration of the acoustic emission (AE) signal. The purpose of this work is to assess the sensitivity of the AE parameters to the change in the dislocation slip systems using an aluminum single crystal as a test piece. The sample surface has been polished and analyzed by scanning electron microscopy and EBSD. The localized deformation test has been carried out on an instrumented tribometer by moving a conical indenter around the circle with a radius of 100 μm under a constant load of 2 N. The advantage of such a test is its ability to plastically deform the surface continuously in all crystallographic directions, preserve the stationary conditions for external factors and ensure the optimal signal-to-noise ratio for recording the AE signal. It is established that, depending on the direction of scratching, the hardness and the AE power exhibit opposite trends, both following the anisotropic properties of a cubic crystal lattice, while changing the configuration of active slip systems can be monitored using an interferometer according to characteristic traces of the slip lines on the polished surface of the sample near еру trace indenter. It is shown that the direction of scratching affects not only the energy of the AE signal, but also its spectral characteristics, in particular, the median frequency, and the extremes in the AE power diagram do not coincide with the extremes in the median frequency diagram.
Source: Letters on Materials
Language: English
Subfield: Metals and Alloys
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2921075441