The effect of Nb element adding on the thermodynamic parameters, corrosion and structural properties of NiTiZr alloy

Enhancing the resistance to corrosion in bioengineering materials holds significant importance for medical applications. The exploration of augmenting the biocompatibility of NiTi-based shape memory alloys is a compelling area of investigation across various disciplines. In this particular study, Ni40-xTi50Zr10Nbx (x = 1, 2, 3, 4, and 5 at.%) with a consistent atomic percentage of Ti and Zr underwent examination. The objective was to enhance the alloy's biocompatibility by substituting Nb for Ni. The investigation included an analysis of the martensitic phase transformation using Differential Scanning Calorimetry (DSC) measurements. The introduction of Nb as an additive exhibited an adverse effect on the martensitic phase transformation, potentially causing a shift in composition within the phase diagram. Tafel testing and electrochemical impedance spectroscopy conducted in a simulated body fluid (SBF) demonstrated that the incorporation of Nb improved the corrosion resistance of the alloy. This improvement was attributed to an increase in the thickness of the protective oxide layer at the interface between the alloy and electrolyte. By replacing an optimal proportion of Ni with Nb, the biocompatibility of the NiTiZr-based alloy was enhanced while preserving its shape memory characteristics.