Effect of laser microcutting on thermo-mechanical properties of NiTiCu shape memory alloy

The machining of shape memory alloys (SMAs), such as NiTi based alloys, is a very interesting and relevant topic for several industrial applications in the biomedical, sensor and actuator fields. Laser technology is one of the most suitable methods for the manufacturing of products in the aforementioned fields, mainly when small and precise features have to be included. Due to the thermal nature of this process, study of its effect on the functional properties of these materials is needed. Except for binary NiTi, few results on the laser machining of NiTi based alloys are available in the literature. In this work, thin sheets of Ni40Ti50Cu10 (at.%) were processed by a fibre laser and the effect of process speed on the material properties was analysed. Scanning electronic microscopy was adopted for observation of the laser cut edges' morphology. Chemical composition of the processed material was evaluated by energy dispersion spectroscopy and nanohardness measurements were used to estimate the heat affected zone. SMA functional properties were studied on both base and laser machined material. These characteristics are affected by laser machining for the presence of melted material; this effect can be minimised by increasing the laser process speed.