Origin of Burst-Type Acoustic Emission in Unflawed 7075-T6 Aluminum

Tensile tests were used to study the acoustic emission from several 7075-T6 aluminum plates. Specimens from one plate produced a large burst-type emission in addition to the continuous emission. Metallographic and fracture surface studies indicated that the burst-type emission resulted from the brittle fracture of large primary inclusions in the microstructure.