Effect of Bias Voltage on Microstructure and Mechanical Properties of Ni3Al Films

A series of Ni3Al films were prepared by magnetron sputtering at different bias voltages. Then the effect of bias voltage on the composition, deposition rate, microstructure, hardness and fracture toughness were studied by XPS, XRD, SEM, AFM nanoindentation and End digital microhardness tester. The results show that introducing the bias voltage can increase the kinetic energy of the ic Tharged ions during sputtering, and thus significantly improve deposition rate, the density of the internal structure and the surf smoothness of Ni3Al films. In addition, the introduction of appropriate bias voltage can induce the formation of amorphous/nanocrystalline composite structure to improve the crystallinity of the films. The wrapped nanocrystalline composite with biphasic structure provides a large number of grain boundaries. Addr strengthen the blocking effect on dislocations, leading to the dislocation stacking at the grain boundary and resulting in the incre hardness. Meanwhile, the large number of grain boundaries also consume the energy of crack propagation to inhibit the generation macrocracks, and significantly enhance the fracture toughness of Ni Al films.