Influence of addition of carbon nanotubes on structure-properties of Cu-Al-Ni shape memory alloys

摘要

The influence of the addition of 0.2 wt-% carbon nanotubes on the microstructure and mechanical properties of Cu based shape memory alloy with a composition of Cu-11.5 wt-%Al-4.5 wt-%Ni were investigated using optical microscopy, X-ray diffraction, scanning electron microscopy and a universal testing machine. The experimental results show that the carbon nanotubes' (CNTs') addition has an effective influence on the martensite-austenite transformation temperatures, type, behaviour and morphology. Furthermore, the addition of CNTs can control the grain size and thus the tensile strength, elongation, fracture stress-strain, yield strength and shape memory effect can be enhanced. Remarkably, the shape recovery ratio reached ～68% of the original shape; this can be attributed to the precipitation and formation of the CNTs into the microstructure, effectively on the grain boundaries, which can help to reduce/relief the concentration of internal stress.