Thermal expansion behavior and elevated temperature elastic properties of an interpenetrating metal/ceramic composite

Kurzfassung

The thermal and elastic behavior of an interpenetrating metal ceramic composite (IMCC), consisting of ceramic foam with 74 % open porosity and an AlSi10Mg light-weight aluminum alloy was investigated at elevated temperatures. The elastic properties of the IMCC and its individual components were determined by ultrasonic phase spectroscopy and resonant frequency damping analysis (RFDA) at RT, showing a highly isotropic behavior for the IMCC. The directional elastic modulus measured at elevated temperature by RFDA decreased from about 110 GPa at room temperature to 80 GPa at 500°C. The elastic modulus temperature curve shows a clear hysteresis for the IMCC, but not for the individual components. Dilatometry experiments revealed the onset of a hysteresis effect in the CTE curve between 260 and 285°C. The hysteresis behavior could be explained by internal stress relaxation, reduction of micro voids and interfacial detachment and assigned to characteristic areas of the hysteresis curve. The associated behavior of the elastic modulus over the temperature range was investigated in detail, and the hysteresis behavior, observed for the first time in the literature was assigned and explained.