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<p>Ti–12Mo–6Zr–2Fe (TMZF) alloy, characterized by its low elastic modulus and high strength-to-weight ratio, is a promising candidate for biomedical implants. However, its application in biomedical fields remains limited due to an incomplete understanding of the corrosion and tribological synergism in simulated body fluid (SBF). This study systematically investigates the phase composition, microstructural evolution, and biocorrosion and tribology behaviors of laser powder bed fusion (LPBF) fabricated TMZF alloys before and after solution treatment (ST). The optimal LPBF parameter was achieved at a linear laser energy density of 200&#xa0;J/m, resulting in a relative density of 99.96% ± 0.02% and surface roughness of 5.27&#xa0;μm, with porosity effectively suppressed. Following solution treatment at 900&#xa0;℃ for 1&#xa0;h, the columnar grains of the LPBF-fabricated (AF TMZF) alloy recrystallized into equiaxed grains, and nanoscale orthorhombic <i>α</i>″ martensite phases precipitated within the <i>β</i>-phase matrix via stress-triggered martensitic transformation. This process was driven by two synergistic factors: (1) the high dislocation density and residual stress of LPBF alloy, and (2) local <i>β</i>-stabilizer depletion during ST. Consequently, AF TMZF exhibited a 69% lower corrosion current density (0.35 ± 0.02 vs. 1.16 ± 0.01&#xa0;μA&#xa0;cm<sup>−2</sup>) and a 271% higher passive film impedance (0.26 vs. 0.07&#xa0;MΩ&#xa0;cm<sup>2</sup>) in SBF than ST TMZF, attributed to its bimodal microstructure of fine equiaxed grains and nanoscale cellular substructures, combined with the inherent passivity of single-phase <i>β</i>-type Ti alloys. In contrast, the <i>α</i>″ phase precipitation in ST TMZF introduced interfacial heterogeneity, generating potential differences at boundaries between <i>β</i> and <i>α</i>″ phase that accelerated passive film rupture. Moreover, the ST TMZF exhibited enhanced microhardness and tribological performance in SBF solution, due to precipitation strengthening by <i>α</i>″ phase. This study elucidates how <i>α</i>″ phase precipitation modulates passive film formation and stability, establishing microstructure–property relationships for corrosion and tribology in LPBF TMZF, critical for its clinical adoption as a durable biomedical implant.</p>

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Heat treatment effect on corrosion and tribological behavior of LPBF β-type Ti–12Mo–6Zr–2Fe (TMZF) alloy in SBF

  • 期刊论文

  • 发表日期：

    2026年1月4日

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  • Chenhong Ning,
  • Qingkun Chu,
  • Zhen Dong,
  • Jiangqi Zhu,
  • Min Liu,
  • Yanli Dou,
  • Xingchen Yan,
  • Zhihui Zhang

摘要

Ti–12Mo–6Zr–2Fe (TMZF) alloy, characterized by its low elastic modulus and high strength-to-weight ratio, is a promising candidate for biomedical implants. However, its application in biomedical fields remains limited due to an incomplete understanding of the corrosion and tribological synergism in simulated body fluid (SBF). This study systematically investigates the phase composition, microstructural evolution, and biocorrosion and tribology behaviors of laser powder bed fusion (LPBF) fabricated TMZF alloys before and after solution treatment (ST). The optimal LPBF parameter was achieved at a linear laser energy density of 200 J/m, resulting in a relative density of 99.96% ± 0.02% and surface roughness of 5.27 μm, with porosity effectively suppressed. Following solution treatment at 900 ℃ for 1 h, the columnar grains of the LPBF-fabricated (AF TMZF) alloy recrystallized into equiaxed grains, and nanoscale orthorhombic α″ martensite phases precipitated within the β-phase matrix via stress-triggered martensitic transformation. This process was driven by two synergistic factors: (1) the high dislocation density and residual stress of LPBF alloy, and (2) local β-stabilizer depletion during ST. Consequently, AF TMZF exhibited a 69% lower corrosion current density (0.35 ± 0.02 vs. 1.16 ± 0.01 μA cm−2) and a 271% higher passive film impedance (0.26 vs. 0.07 MΩ cm2) in SBF than ST TMZF, attributed to its bimodal microstructure of fine equiaxed grains and nanoscale cellular substructures, combined with the inherent passivity of single-phase β-type Ti alloys. In contrast, the α″ phase precipitation in ST TMZF introduced interfacial heterogeneity, generating potential differences at boundaries between β and α″ phase that accelerated passive film rupture. Moreover, the ST TMZF exhibited enhanced microhardness and tribological performance in SBF solution, due to precipitation strengthening by α″ phase. This study elucidates how α″ phase precipitation modulates passive film formation and stability, establishing microstructure–property relationships for corrosion and tribology in LPBF TMZF, critical for its clinical adoption as a durable biomedical implant.