IDT Sensors for Detection of Heat Sensitization in Aluminum Alloys

An innovative surface acoustic wave (SAW) sensor for in situ detection and real-time monitoring of heat sensitization in 5XXX series aluminum alloys will be developed. These active sensors generate ultrasonic Rayleigh waves at a fundamental frequency and then detect higher harmonics of that frequency produced when the sound waves scatter off of regions of beta phase Al3Mg2 that form during heat sensitization. The degree of harmonic sound detection will be correlated to how the alloy would respond to the ASTM-G67 chemical test. This will create a calibrated method for direct in situ measurement of changes in physical properties of the alloy as well as the risk of future anodic degradation, stress corrosion cracking or exfoliation or alternatively, the expected remaining life of the material. The sensors will be durable and field deployable either for spot checks for material or permanent emplacement in the structure of interest. Due to the long range of Rayleigh waves, the surface are coverage standard for the sensor will easily be met. The low power requirements are consistent with methods of self powering. Operation in adverse conditions will be demonstrated and are not expected to pose any barriers for the technology.