Microstructural, mechanical, and biocompatibility properties of Ti–Cu/B4C composites for biomedical applications

Abstract

This study investigated the effects of B4C on the microstructural, mechanical, and biocompatibility properties of Ti–Cu/B4C composites produced by powder metallurgy. Different amounts of B4C (3, 6, 9, and 12 %) were added to the Ti–Cu matrix. XRD results showed that Ti2Cu, α-Ti, TiB, and B4C phases formed in the microstructure. The addition of B4C and the phases forming in the microstructure resulted in significant increases in the hardness and wear resistance of the composites. SEM images of the wear surfaces showed that the abrasive wear mechanism was dominant. Biodegradability analyses showed that sodium, found in trace amounts in the structure of the alloys, and calcium, released from the structure of B4C into the medium, were the least at the addition of 6 % B4C. Considering the reduced amount of phosphate in the medium, it was found that the mass gain observed in the specimens was due to the deposition of calcium-phosphate precipitates on the surface of the composites. This result suggested that Ti–Cu/B4C alloys were bioactive for bone and may provide osteointegration. Indirect MTT analysis with bone marrow mesenchymal stem cells showed that the specimens were cytotoxic at an acute dose on the first day. However, the cytotoxic effect diminished when they were kept in the PBS medium and replaced every other day for 28 days. Notably, the composite specimen with the addition of 6 % B4C demonstrated maximum cytocompatibility. Consequently, it indicated that adding B4C to the alloy improved osteogenic properties, although it partially increased copper release into the medium.