A metastable β-type Zr-4Mo-4Sn alloy with low cost, low Young's modulus and low magnetic susceptibility for biomedical applications

By alloying and thermo-mechanical treatment, a novel low-cost metastable β-type Zr-4Mo-4Sn alloy was designed and fabricated for biomedical applications. Upon solution treatment plus quenching, the β-type Zr-4Mo-4Sn alloy exhibits a combination of low Young's modulus (48 GPa) and low magnetic susceptibility (1.22 × 10⁻⁶ cm³ g⁻¹). This low magnetic susceptibility (χ) is reasonably attributed to the choice of alloying components with low χ, i.e., Zr (χ_Zr = 1.32 × 10⁻⁶ cm³ g⁻¹), Mo (χ_Mo = 0.75 × 10⁻⁶ cm³ g⁻¹) and Sn (χ_Sn = 0.03 × 10⁻⁶ cm³ g⁻¹). An analysis of single-crystal elastic constants and Hill approximation indicated that in comparison to binary β-type Ti-based alloys, the present β-type Zr-4Mo-4Sn alloy possesses lower bcc-structural (β-phase) stability represented by its lower C′ and much lower C₄₄, resulting in the ultralow Young's modulus of Zr-4Mo-4Sn alloy.