Selective laser melting of novel titanium-tantalum alloy as orthopaedic biomaterial

Abstract

Selective laser melting (SLM) is an additive manufacturing (AM) technique that is capable of fabricating complex functional three-dimensional (3D) metal parts of high relative density with the complete melting and fusion of powders. As a powder bed fusion technology, SLM has the potential in expanding the materials library by formation of alloys that were previously difficult to achieve from metal powder mixtures that can be customised according to the application requirements. Titanium-tantalum (TiTa) is a potential material for biomedical applications due to its high strength to modulus ratio. However, it is still not widely used due to the difficulties in obtaining this alloy. SLM is chosen as the method to form this alloy due to its versatility in processing metallic materials and good results obtained from commercially pure titanium (cpTi) and Ti6Al4V. This research aims to develop TiTa as a potential material for biomedical applications. The study also paves the way for better understanding and control of the SLM process in porous lattice structure fabrication through statistical modelling. Firstly, the TiTa formation is studied to understand the forming mechanism and the effect of SLM processing parameters on the resulting density and macrostructure of the parts. The processing window and optimised parameters based on optimum relative density achieved are then presented. Secondly, the resulting microstructure of TiTa parts was examined and characterised to facilitate the understanding of the SLM forming process. The SLM TiTa parts exhibited a microstructure characterised by homogenous β titanium and tantalum matrix with randomly distributed tantalum particles. Thirdly, the mechanical properties of SLM TiTa parts is benchmarked against the more commonly used cpTi and Ti6Al4V. The TiTa Young's modulus is Abstract ii 75.77 ± 4.04 GPa and has yield strength of 882.77 ± 19.60 MPa, ultimate tensile strength of 924.64 ± 9.06 MPa and elongation of 11.72 ± 1.13 %. It is found that SLM TiTa parts have lower Young's modulus and comparable strength to Ti6Al4V and cpTi. Fourthly, the effect of SLM processing parameters on lattice structure properties is statistically modelled and analysed using regression analysis and analysis of variance (ANOVA). It is shown that laser power and layer thickness are dominant factors in affecting the properties of the lattice structures. Lastly, the properties of SLM TiTa lattice structures are also benchmarked against lattice structures fabricated using cpTi and Ti6Al4V. With 59.79 ± 0.68 % porosity, TiTa exhibits an elastic constant of 4.57 ± 0.09 GPa and yield strength of 151.93 ± 4.04 MPa which provides a higher strength to elastic constant ratio when compared to Ti6Al4V and cpTi. The same conclusions are drawn for compressive and tensile properties. Cell culture study using osteoblastlike SAOS-2 cells found that SLM TiTa has similar biological response to cpTi and Ti6Al4V. These favourable findings ascertained the feasibility of SLM TiTa as a biomaterial and contributed to the scie...

Balancing the customization and standardization: exploration and layout surrounding the regulation of the growing field of 3D-printed medical devices in China

“…Different orthopedic implants are typical applications of these powdered metals for 3D printing. Since many bone tissues in the human body have varying porosity, 3D uneven structures from macro-to nanoscale, and differing mechanical strength from the outer to the inner section [20,53], orthopedic implants not only need to match this functionally graded structure [54], but also feature sufficient toughness, strength, tribology, biocompatibility, and wear resistance between artificial joints [53,55], which often require significant geometric optimization and surface modification [56]. These criteria are challenging to fulfill for the structure and materials of orthopedic implants and make it difficult to realize through traditional manufacturing methods.…”

“…These criteria are challenging to fulfill for the structure and materials of orthopedic implants and make it difficult to realize through traditional manufacturing methods. Titanium alloy and tantalum are well-known for their beneficial mechanical properties, corrosion resistance, and biocompatibility [53,57]. With the support of 3D printing technology, these powdered metals can well manufacture implants that meet the requirements and are more conducive to osseointegration.…”

Fusão em leito de pó a laser da liga de Co-Cr-Mo: propriedades mecânicas e microestrutura após tratamentos térmicos

“…Um exemplo na área aeroespacial da otimização em componentes estão as turbinas com alívio de peso. Na área médica, se destacam a fabricação de implantes ortopédicos personalizados e com estruturas do tipo lattice, proporcionando redução de peso, diminuindo procedimentos cirurgicos ao longo do tempo e promovendo maior aceitação com os tecidos (SING, 2019).…”

Additive manufacturing and mechanical properties of titanium lattices for biomedical applications

“…Limited literature is available on Ti-Ta alloys manufactured with SLM. Sing et al [32,33,35] have reported the effect of SLM parameters on part quality and mechanical properties for a dense Ti-50Ta alloy (50 wt.% of each element). Despite difficulties in fully melting the tantalum particles, they reported high densification and good mechanical properties compared to cp-Ti and Ti-6Al-4V parts, with dimensional accuracy and mechanical properties affected by printing parameter control (eg.…”