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Open AccessArticle

Linear Versus Nonlinear Acoustic Probing of Plasticity in Metals: A Quantitative Assessment

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Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Avenida Blanco Encalada 2008, Santiago 8370449, Chile
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Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa Maria, Av. España 1680, Valparaíso 2390123, Chile
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Departamento de Ingeniería Química, Biotecnología y Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Avenida Beauchef 851, Santiago 8370456, Chile
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Núcleo de Matemáticas, Física y Estadística, Facultad de Estudios Interdisciplinarios, Universidad Mayor, Manuel Montt 318, Providencia 7500628, Chile
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Author to whom correspondence should be addressed.
Materials 2018, 11(11), 2217; https://doi.org/10.3390/ma11112217
Received: 25 October 2018 / Revised: 2 November 2018 / Accepted: 6 November 2018 / Published: 8 November 2018
(This article belongs to the Section Materials Physics)
The relative dislocation density of aluminum and copper samples is quantitatively measured using linear Resonant Ultrasound Spectroscopy (RUS). For each metallic group, four samples were prepared with different thermomechanical treatments in order to induce changes in their dislocation densities. The RUS results are compared with Nonlinear Resonant Ultrasound Spectroscopy (NRUS) as well as Second Harmonic Generation (SHG) measurements. NRUS has a higher sensitivity by a factor of two to six and SHG by 14–62%. The latter technique is, however, faster and simpler. As a main result, we obtain a quantitative relation between the changes in the nonlinear parameters and the dislocation density variations, which in a first approximation is a linear relation between these differences. We also present a simple theoretical expression that explains the better sensitivity to dislocation content of the nonlinear parameters with respect to the linear ones. X-Ray diffraction measurements, although intrusive and less accurate, support the acoustics results. View Full-Text
Keywords: alloys; nondestructive testing; dislocation density; plasticity; ultrasound; nonlinear acoustics alloys; nondestructive testing; dislocation density; plasticity; ultrasound; nonlinear acoustics
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MDPI and ACS Style

Espinoza, C.; Feliú, D.; Aguilar, C.; Espinoza-González, R.; Lund, F.; Salinas, V.; Mujica, N. Linear Versus Nonlinear Acoustic Probing of Plasticity in Metals: A Quantitative Assessment. Materials 2018, 11, 2217.

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