Volume Magnetic Susceptibility Estimation of α- and β-Phases in Titanium Alloys for Biomedical Applications

Abstract

Metallic medical devices in the human body cause serious artifacts in magnetic resonance imaging owing to the volume magnetic susceptibility (χ_ν) mismatch between the device and tissue around the device. To reduce artifacts, medical devices produced from alloys with χ_ν values of approximately −9 × 10⁻⁶ are required. Controlling the phase constitution is a basic technique used to control the χ_ν value of an alloy, and the χ_ν value of each phase is a fundamental property. In this study, an α+β-type Ti alloy and two β-type Ti alloys were investigated. The estimated χ_ν values of the α-phase of the alloys were similar to or smaller than that of pure Ti. In contrast, the estimated χ_ν values of the β-phase of the alloys were larger than that of pure Ti. Since the χ_ν value of pure Ti is much larger than −9 × 10⁻⁶, the χ_ν values of the β-phases suggested that increasing the volume fraction of the β-phase was not appropriate for producing a Ti alloy with a lower χ_ν value.