Effect of Hafnium on Nickel-Titanium based Thin Film Coating by DC/RF Magnetron Sputtering Technique

Abstract

Ni-Ti-Hf films as shape memory alloys were successfully prepared by magnetron sputtering technique using individual Ti, Ni and Hf targets. The hafnium content was varied from 6% to 30% and the required film composition was achieved by adjusting the power ratio to the targets. The as-deposited films were amorphous; a post deposition annealing was performed at 700 °C to crystallize the Ni-Ti-Hf films. Structural, compositional and phase-transformation studies were carried out on these Ni-Ti-Hf films using X-ray diffraction (XRD) technique, field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and differential scanning calorimetry (DSC), respectively. The effects of the processing parameters on the film composition, phase transformation and film residual stress were analyzed. 

Keywords:  Shape memory alloys, annealing, Ni-Ti-Hf film, magnetron sputtering technique