Athermal ω Phase and Lattice Modulation in Binary Zr-Nb Alloys

Area of Science:

• Materials Science
• Biomaterials Engineering
• Metallurgy

Background:

• Zirconium-based alloys are explored for metallic biomaterials.
• Interference with Magnetic Resonance Imaging (MRI) is a key concern for metallic implants.
• Understanding microstructural characteristics is crucial for developing MRI-compatible alloys.

Purpose of the Study:

• To investigate the microstructural properties of Zr-xat.% Nb alloys (10 ≤ x ≤ 18).
• To correlate microstructural features, specifically the athermal omega phase and lattice modulation, with MRI compatibility.
• To evaluate the potential of Zr-Nb alloys as MRI-compatible metallic biomaterials.

Main Methods:

• Electrical resistivity and magnetic susceptibility measurements were performed.
• Transmission electron microscopy (TEM) was utilized for microstructural observations.
• Analysis of selected area diffraction patterns to identify phase transformations and lattice modulations.

Main Results:

• Zr-Nb alloys with 10 and 12 at.% Nb exhibited a positive temperature coefficient of electrical resistivity and contained the athermal omega phase at room temperature.
• Zr-Nb alloys with 14 and 18 at.% Nb showed an anomalous negative temperature coefficient of resistivity.
• Diffuse satellites, indicative of transverse waves, were observed in the 14 Nb alloy, potentially linked to the resistivity anomaly and athermal omega phase formation.

Conclusions:

• The athermal omega phase and lattice modulation significantly influence the properties of Zr-Nb alloys.
• Controlling these microstructural features leads to reduced magnetic susceptibility, improved deformation properties, and a lower Young's modulus.
• Zr-Nb alloys demonstrate considerable promise as MRI-compatible metallic biomaterials due to their favorable characteristics.