The low modulus β-type Ti-45Nb alloy is a promising new implant alloy due to its excellent mechanical biocompatibility and composition of non-toxic elements. The effect of surface treatments on the evolution of controlled topography and roughness was investigated by means of scanning electron microscopy and optical profilometry. Severe mechanical treatments, for example sand-blasting, or etching treatments in strongly oxidizing acidic solutions, like HF:HNO(3) (4:1) or H(2)SO(4):H(2)O(2) (1:1) piranha solution were found to be very effective. In particular, the latter generates a nanopatterned surface topography which is expected to be promising for the stimulation of bone tissue growth. Compared to Ti and Ti-6Al-4V, the β-type Ti-45Nb alloy requires significantly longer etching durations due to the high chemical stability of Nb. Severe surface treatments alter the passive film properties, but do not deteriorate the outstanding corrosion resistance of the Ti-45Nb alloy in synthetic body fluid environments. The Ti-45Nb appears to have a lower apatite-formation ability compared to Ti. Etching with H(2)SO(4):H(2)O(2) (1:1) piranha solution inhibits apatite formation on Ti, but not on Ti-45Nb.

Currently, additive manufacturing, e.g., selective laser melting (SLM), of biodegradable metals and alloys for implant applications is drawing increasing attention. [1-5] This new class of materials is of highest interest as it enables progressive implant degradation after providing temporary support on the healing processes of the diseased tissue. So, revision surgery, chronic inflammation, or lacking adaptation to growth (regarding diseases at infancy) can be avoided. [6-8] Among the biodegradable alloys, Fe-based systems, especially those on FeMn base, are very promising, e.g., for cardiovascular applications due to their excellent processability, a broad range of tunable mechanical properties, their high integrity during degradation, as well as degradation reactions without hydrogen gas evolution in physiological media. This was reported for a variety of alloy systems prepared by different casting and forming technologies. [7-16] Especially, FeMnC-base alloys are promising candidates due to their higher strength and improved cell compatibility compared with many FeMn systems. [11-15] This work is based on a novel developed FeMnCS alloy, which already shows an attractive combination of mechanical properties under tensile load, corrosion rate, and cell compatibility in the as-cast state, as shown in previous studies. [11,14] However, there are still challenges regarding a more homogenous degradation for good temporary structural integrity, an adequate corrosion rate, as well as improved mechanical properties which are comparable or better than those of clinically applied 316L benchmark steel. Until now, there are only a few published studies on the processing of biodegradable Mg-, Zn-, or Fe-based alloys by means of SLM. [1-4,17-20] However, the layer-by-layer technique offers a flexible production of parts with a high degree of individualization or complex geometries and a high level of function integration, which can often not be generated by conventional manufacturing techniques. [21,22] Furthermore, SLM is a rapid solidification technique, which yields particular microstructural phenomena like grain refinement, extended solid solubility and reduction of quantity, and size of phase segregations. These effects can be very beneficial for the properties of metallic biomaterials as it was already demonstrated by different authors for various nondegradable materials like 316L, Ti-based, or CoCr-based alloys, also partially considering the influence of the SLM building orientation. [21-29] Consequently, the exploitation of advantages of SLM for the production of patient-specific degradable implants with tailored microstructures appears to be a promising approach.

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