Enhanced Functional Fatigue Resistance of Cu-Al-Mn Superelastic wire
bamboo-like grain structure
Abstract
The enhanced fatigue resistance of superelastic Cu-Al-Mn shape memory
wires were investigated via bamboo-like grain structure obtained by
cyclic heat treatment (CHT). It was demonstrated that increasing the
number of CHT cycles can promote the grain growth to a straight grain
boundary, eliminating the triangular structure that generally caused
brittle fracture. In particular, the 5CHT and 7CHT specimens displayed
negligible residual strain subsequent to unloading, following exposure
to cumulative strains ranging from 2% to 10%, thereby showcasing
superior superelasticity. From the functional fatigue test, the fatigue
life of the shape memory wire subjected to 5 CHT cycles exceeds 4650
cycles at 5 % strain, which is more than 5 times that of traditional
polycrystalline quenched samples.