Effect of the Al–CNT interlayer on the tensile elastic modulus of Al matrix composites with random dispersion of CNTs

This work studies the effect of Al4C3 layer formation in the carbon nanotube (CNT)–Al interface on the tensile elastic modulus of the resulting composite material, focusing on the thickness of this layer. 3-D models combining discrete element model and finite element analysis (FEA) were used in order to simulate the behavior of composites with different volume fractions of CNTs randomly dispersed into the Al matrix. Layers of 1, 5, 10 and 15 nm were modeled, affecting the CNTs according to the expected interfacial reaction. Estimations were compared to those obtained in a previous work using unit cell models for an ordered composite. Results showed that the presence of this interface increases total reinforcement volume fraction. Besides, elastic modulus of the composites increased with CNT volume fraction, while the increase in the interface thickness also provoked an increment in the Young’s modulus, attributed to the combined reinforcement effect of CNT and Al4C3. Estimations for the 3-D models were between maxima and minima values predicted by longitudinal and transversal moduli for ordered composites. Results also showed the importance of the use of more realistic FEA models for improving the predicting ability of this method for predicting the mechanical behavior of composites.