Elevated temperature compressive properties and energy absorption response of in-situ grown CNT-reinforced Al composite foams

Carbon nanotube (CNT) reinforced Al composite foams were successfully fabricated by the combination of an in-situ chemical vapor deposition (CVD), short-time ball-milling and space-holder method. The CNTs are homogeneously dispersed and embedded in the Al foam matrix after 90 min ball-milling while maintaining the structural integrity. Both compressive properties and energy absorption capacity of the composite foams increase with the increment of CNT content but decrease with the temperature rising between 25 and 250 °C. The compressive yield strength and the plateau stress of 3.0 wt%-CNT/Al composite foams maintain 16.8 and 20.2 MPa at 150 °C, respectively, which are much higher than the corresponding yield stress (5.7 MPa) and plateau stress (8.6 MPa) of the pure Al foam. Especially, the energy absorption capacity of the 3.0 wt%-CNT/Al composite foams reaches 19.8 MJ/m3 at 150 °C, which is ~2.5 times higher than that of pure Al foam. Fracture analysis shows that the failure mode of the Al foam changes from ductile type to brittle type combined with ductile type, as a result of the CNT addition in the matrix.