Mechanical properties and failure mechanisms at high temperature in carbon nanotube reinforced copper matrix nanolaminated composite

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Copper matrix composites are widely used as strong conducting materials. Mechanical properties and failure behavior at high temperatures are investigated for carbon nanotubes/copper matrix nanolaminated composites with well-balanced strength and ductility in this work. Tensile strength of the composite decreased considerably as temperature increased because of matrix softening and Cu grain coarsening. Deformation mechanism is controlled by pipe diffusion mechanism at 573 K, while lattice diffusion at 773 K. The failure behavior is shown to transform from interfacial debonding of CNT-matrix to Cu matrix failure as the temperature increases. CNTs are pulled-out on fractured surfaces at both room and high temperature, but with different morphologies. Elemental analysis and microstructural observations indicated that the interface shear strength is between the matrix strength of 75 MPa at 773 K and 320 MPa at room temperature. The results shed light on designing advanced copper matrix composites for applications at high temperature.