Acoustic Microscopy of Advanced Aerospace Materials

Ultrasonic Scanning Acoustic Microscopy (SAM) is useful for material elastic property quantification, surface and subsurface crack initiation detection and growth estimation, and fiber-matrix interfacial damage assessment [1–5]. The advantage of the method is that the imaging technique can provide the crack sizing information while helping in the detection of interface degradation and early crack initiation so that their growth can be monitored during interrupted fatigue tests. The scanning acoustic microscope technique has been applied in the past to metal matrix composites subjected to both room temperature and elevated temperature fatigue cycling in addition to thermomechanical fatigue (in-phase and out-of-phase) conditions. In this paper, we present results obtained from an in-house developed acoustic microscope operating in the frequency range of 25–200 MHz. Results of characterization of many aerospace materials such as metal matrix and ceramic matrix composites and titanium alloys are provided to demonstrate the versatility of the system.