Effect of Nb Content on the Microstructure and Superelastic Behavior of Low Modulus Ti-Nb-Sn Biomedical Alloys

초록

This study investigates the effect of Nb content on the microstructure and recovery strain of Ti-xNb-8Sn (x = 10-13 at.%) biomedical alloys aimed at achieving a favorable balance between low elastic modulus and superelastic performance. Following solution treatment at 1173 K for 0.5 h, all alloys comprise a dominant beta-phase matrix with minor Ti3Sn precipitates. The beta grain size is similar between 10 and 11Nb alloys, but decreases markedly from 76.4 to 33.5 mu m with increasing Nb content from 11 to 13 at.%. A distinct recrystallization texture develops and weakens as Nb content rises. The omega phase is entirely suppressed due to the strong beta-stabilizing effect of Sn and Nb, while nanodomain formation is enhanced at higher Nb contents. These nanodomains facilitate a recovery strain of 1.2-2.1% under tensile loading to 3% strain. The apparent elastic modulus increases from 39.2 to 50.3 GPa with higher Nb addition, attributed to grain refinement and increased Ti3Sn volume fraction in the 13Nb alloy. The combination of low elastic modulus and appreciable recovery strains highlights the potential of these alloys for biomedical applications.

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