Temperature dependent strengthening mechanisms and yield strength for CNT/metal composites

Strengthening mechanisms in CNT/metal composites are significant guidelines on composites design. However, the strengthening mechanisms at high temperatures have few been reported. In this work, the evolution of four common strengthening mechanisms in CNT/metal composites, including load transfer strengthening, grain refinement strengthening, enhanced dislocation density strengthening and Orowan strengthening, with temperature was investigated by our developed theoretical models. Then by considering those temperature dependent strengthening mechanisms, a temperature dependent yield strength model for CNT/metal composites was established. Further, the effects of residual thermal stress and quicker softening of matrix on the temperature dependent yield strength of composites were also taken into account. Good agreement is obtained between the model predictions and available experimental results. This study contributes a simple method to predict the yield strength for CNT/metal composites over a wide range of temperatures. In addition, the contribution of each strengthening mechanism to the yield strength of composites at different temperatures was extensively discussed. Some useful suggestions for the design of new CNT/metal composites with high yield strength at elevated temperatures were provided.