Structures and properties of biocompatible Ti-Zr-Nb-Fe-Mo medium entropy alloys

Abstract

Biomedical implants require high yield strength, low Young's modulus and high ductility synergistic effect. The “stress shielding” caused by the high Young's modulus of most existing high-entropy alloys limited their applications. In this work, a body-centered cubic solid solution Ti45Zr37Nb16Fe1Mo1 (at.%) medium entropy alloy with low Young's modulus (~63 GPa), high tensile elongation (~25 %), and good corrosion resistance (Ecorr = −264 mV, Icorr = 0.15 μA·cm−2) was designed and fabricated. The admissible elastic strain of cold rolled alloy has increased 50% compared with as-cast alloy (~1.12 %). Furthermore, the coefficient of friction of the cold rolled alloy was higher than the as-cast alloy due to the stress-induced orthorhombic α'' martensite formation. Their mechanical properties can be achieved by tuning the fraction of β-stabilizing elements to obtain a metastable single body-centered cubic phase.