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Commonly used severe plastic deformation (SPD) methods are suitable for fabrication of bulk nano and ultrafine-grained metals. Drawbacks of these methods include durability of dies, geometrical restrictions and reduced ductility of the products. In this study, two common machining techniques used in manufacturing of orthopaedic components, turning and milling, were applied on 316L stainless steel as surface SPD to refine the surface microstructures of the workpiece. Machining with optimised parameters resulted in substantial grain refinement down to 98 nm on the surfaces. Biological experiments showed up to ∼70% and ∼280% increased bone cell density on milled and turned samples compared to conventionally machined 316L stainless steel at 5 days, which was correlated with nanocrystallisation and nanoroughness of the samples. [ABSTRACT FROM AUTHOR]

Due to their remarkable mechanical properties and biocompatibility, zirconia toughened alumina (ZTA) based composites are preferred materials for dental and orthopedic uses. This study focuses on the production and characterization of hexagonal boron nitride (BN) containing ZTA ceramics. To achieve this, we formulated composite systems with a composition of 70Al 2 O 3 -(30-x)YSZ-(x)BN (in vol%, where x ranges from 1 to 5). These mixtures were densified via spark plasma sintering (SPS) at a temperature of 1350 °C under a pressure of 40 MPa, with a dwell time of 5 min. The densification, resulting microstructure, and mechanical properties, including Vickers hardness and indentation fracture toughness, were thoroughly examined. All ZTA-BN composites achieved sintering densities exceeding 98.5% of their theoretical values. Incorporating BNs into ZTA composites increased fracture toughness by ∼55% while maintaining Vickers hardness values. Notably, crack deflection mechanism played a dominant role in toughening, particularly for the composite containing 3 vol% BNs. Furthermore, in vitro biocompatibility assessment of the YZTAB3 sample demonstrated that the composite had no cytotoxic effects towards human bone cells, indicating its potential for biomedical applications. [ABSTRACT FROM AUTHOR]