Microstructure of equiatomic and non-equiatomic Ti-Nb-Ta-Zr-Mo high-entropy alloys for metallic biomaterials

The microstructures of equiatomic TiNbTaZrMo (Ti20Nb20Ta20Zr20Mo20—subscript numerals denote at.%) and non-equiatomic Ti2.6NbTaZrMo (Ti39.4Nb15.2Ta15.2Zr15.2Mo15.2) high-entropy alloys (HEAs) were investigated for use in metallic biomaterials, and discussed based on their thermodynamics. Equiaxial dendrite structures were observed in the as-cast specimens. Ta, Nb, and Mo were abundant in the main dendrite phase with a body centered cubic (bcc) structure, while Ti and Zr showed a tendency to be abundant in the inter-dendrite region with a bcc structure. The distribution of the constituent elements can be explained through the distribution coefficients during solidification estimated using thermodynamic calculations. The thermodynamic calculations focusing on the solidification process were effective not only for the evaluation of the solidification microstructure, but also for the design of Ti-Nb-Ta-Zr-Mo-based HEAs. The non-equiatomic Ti2.6NbTaZrMo HEA (Ti39.4Nb15.2Ta15.2Zr15.2Mo15.2) was designed based on thermodynamic calculations and the solidification microstructure was studied.Nagase T., Todai M., Hori T., et al. Microstructure of equiatomic and non-equiatomic Ti-Nb-Ta-Zr-Mo high-entropy alloys for metallic biomaterials. Journal of Alloys and Compounds, 753, 412. https://doi.org/10.1016/j.jallcom.2018.04.082

Development of non-equiatomic Ti-Nb-Ta-Zr-Mo high-entropy alloys for metallic biomaterials

Nobel non-equiatomic Ti-Nb-Ta-Zr-Mo high-entropy alloys (HEAs) for metallic biomaterials (bio-HEAs) were designed and developed. The pseudo-binary phase diagrams focusing on solidification were constructed by thermodynamic calculations. The shifting the alloy composition of the equiatomic TiNbTaZrMo bio-HEA can realize the drastic improvement of the deformability. Notably, the non-equiatomic Ti, Zr-rich composition stimulated the molecular interaction between biological cells and bio-HEA, indicating the possibility of the proposed non-equiatomic Ti-Nb-Ta-Zr-Mo HEAs as an advanced biomaterial for bone tissue engineering applications. This is the first achievement for the alloy design including the control of alloy composition for the development of new bio-HEAs.Hori T., Nagase T., Todai M., et al. Development of non-equiatomic Ti-Nb-Ta-Zr-Mo high-entropy alloys for metallic biomaterials. Scripta Materialia, 172, , 83. https://doi.org/10.1016/j.scriptamat.2019.07.011

Additive manufacturing of dense components in beta‑titanium alloys with crystallographic texture from a mixture of pure metallic element powders

The fabrication of dense components composed of Ti-based alloys, i.e., Ti-X (X = Cr, Nb, Mo, Ta) alloys, from a mixture of pure elemental powders was achieved using selective laser melting (SLM) process. The Ti-Cr alloys comprise β-Ti single-phase components without any non-molten particles and macroscopic defects. The crystallographic texture of these β-Ti-Cr alloys can be controlled effectively by optimizing the build parameters. The development of {001}〈100〉crystallographic orientation during the SLM process is discussed based on the solidification process focusing on the columnar cell growth in the melt pool. These results demonstrate the possibility of fabricating the Ti-based alloy components with well-developed crystallographic texture from the mixture of pure elemental powders using the process of SLM.Nagase T., Hori T., Todai M., et al. Additive manufacturing of dense components in beta‑titanium alloys with crystallographic texture from a mixture of pure metallic element powders. Materials and Design, 173, 107771. https://doi.org/10.1016/j.matdes.2019.107771

Systemic amyloidosis by LPL

We present the case of an 81-year-old woman with right shoulder discomfort and right supraclavicular lymph node swelling who referred to our hospital. Blood tests results showed normal immunoglobulin levels, but free light chain assay showed abnormal κ/λ ratio. Serum immunoelectrophoresis detected immunoglobulin G-λ type M proteins. 18F-fluorodeoxyglucose computed tomography revealed swelling of the right supraclavicular and mediastinal lymph nodes. Biopsy of the right supraclavicular lymph node showed a mixture of small lymphocytes with plasma cell-like round cells that were positive for cell surface CD20, CD138, CD56, IgG and λ, and negative for transthyretin and amyloid A. They had a Congo red stain-positive, glass-like surrounding structure and apple-green birefringence was observed under polarized light. Duodenal, gastric, and skin biopsies also showed amyloid deposits. We diagnosed the patient with lymphoplasmacytic lymphoma complicated by systemic light-chain amyloidosis. Rituximab monotherapy led to complete metabolic response. Systemic amyloidosis is a rare complication of B-cell lymphoma; however, the possibility of amyloidosis should be considered, even in patients with lymphadenopathy