FRACTURE OF BORON PARTICLES IN 2219-ALUMINUM AS A KNOWN ACOUSTIC-EMISSION SOURCE

Boron particles have been introduced into 2219 aluminum using a powder metallurgy approach. The only sources of detectable acoustic emission during deformation of the resulting material are decohesion of the boron particles from the matrix and particle fracture. The energy released by fracture of the boron particles during deformation was estimated from elasticity theory using measured diameters of the individual fractures. The energy in the acoustic emission signals produced by particle fracture (the integral of the signal voltage squared) was found to be proportional to the fracture energy released. Fracture energies were in the range 1-7 ergs for the larger fractures. The relation found between fracture energy and acoustic emission signal energy can be used to estimate the energy released by other comparable acoustic emission sources in samples of similar geometry from their acoustic emission signals. During the course of the acoustic emission measurements, the response of an rms voltmeter to an individual acoustic emission signal was found to be proportional to the energy of the signal. © 1990.