Location

La Jolla, CA

Start Date

1-1-1991 12:00 AM

Description

An important aspect of nondestructive evaluation is materials characterization, in particular, detection of changes in the microstructure, affecting the mechanical properties. The goal of this project is to correlate the mechanical properties of high strength alloys with nonlinear acoustical properties of the materials. Many high strength alloys are precipitation hardened, and therefore, their mechanical properties are dependent on microstructural changes during thermal aging. Since the precipitates are formed by diffusion a property sensitive to the precipitation changes is the electrical resistivity. Standard ultrasonic techniques, on the other hand, have been unreliable in microstructural characterization, since in these alloys linear acoustic properties (e.g. sound velocity, attenuation) change by no more than 1%. Literature indicates however that nonlinear acoustical properties change by roughly 50% [1]. From this evidence it appears a nonlinear acoustic technique would be an additional method to examine microstructural changes in precipitation hardened materials.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

10B

Chapter

Chapter 7: Characterization of Materials

Section

Properties

Pages

1663-1671

DOI

10.1007/978-1-4615-3742-7_71

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Nonlinear Acoustics, a Technique to Determine Microstructural Changes in Materials

La Jolla, CA

An important aspect of nondestructive evaluation is materials characterization, in particular, detection of changes in the microstructure, affecting the mechanical properties. The goal of this project is to correlate the mechanical properties of high strength alloys with nonlinear acoustical properties of the materials. Many high strength alloys are precipitation hardened, and therefore, their mechanical properties are dependent on microstructural changes during thermal aging. Since the precipitates are formed by diffusion a property sensitive to the precipitation changes is the electrical resistivity. Standard ultrasonic techniques, on the other hand, have been unreliable in microstructural characterization, since in these alloys linear acoustic properties (e.g. sound velocity, attenuation) change by no more than 1%. Literature indicates however that nonlinear acoustical properties change by roughly 50% [1]. From this evidence it appears a nonlinear acoustic technique would be an additional method to examine microstructural changes in precipitation hardened materials.