IN-SITU CHARACTERIZATION OF SINTERING PROPERTIES WITH NON-CONTACT ULTRASONIC MEASUREMENTS

摘要

In-situ characterizations of green state part density and sintering state have long been desired in the powder metal community. Recent advances in non-contact electromagnetic acoustic transducer (EMAT) technology have enabled in-situ evaluations of the acoustic attenuation and velocity as sintering proceeds. Pure aluminum (99.999 percent) and aluminum alloy powders were prepared with high-pressure gas atomization (HPGA). The powders were pressed in a uniaxial die and examined with acoustic waves for changes in velocity and attenuation during sintering. The changes in acoustic properties were correlated with sample microstructures and mechanical properties. Evolution of the acoustic echo train during sintering is shown to provide information on the state of sintering as well as having the potential for detection of interior flaws.