Effect of cold rolling on fatigue crack propagation of TiNi/Al6061 shape memory composite

A TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in the metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/Al6061 shape memory alloy (SMA) composite was fabricated by the hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with 0%, 3.2%, 5.2% and 7% volume fraction of TiNi alloy fiber, respectively. A fatigue test has been performed to evaluate the crack initiation and propagation for the TiNi/Al6061 SMA composite fabricated by this method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also been done under both room temperature and high temperature conditions. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.