Progress in partially degradable titanium-magnesium composites used as biomedical implants

Structural Phenomena Introduced by Rotary Swaging: A Review

Rotary swaging is an industrially applicable intensive plastic deformation method. Due to its versatility, it is popular, especially in the automotive industry. Similar to the well-known methods of severe plastic deformation (SPD), rotary swaging imparts high shear strain into the swaged materials and thus introduces grain refinement down to a very fine, even ultra-fine, level. However, contrary to SPD methods, one of the primary characteristics of which is that they retain the shapes and dimensions of the processed sample, rotary swaging enables the imparting of required shapes and dimensions of workpieces (besides introducing structure refinement and the consequent enhancement of properties and performance). Therefore, under optimized conditions, swaging can be used to process workpieces of virtually any metallic material with theoretically any required dimensions. The main aim of this review is to present the principle of the rotary swaging method and its undeniable advantages. The focus is primarily on assessing its pros and cons by evaluating the imparted microstructures.

Microstructure, Mechanical Properties, In Vitro Biodegradability, and Biocompatibility of Mg-Zn/HA Composites for Biomedical Implant Applications

Recently, Mg-Zn/hydroxyapatite (HA) composites have attracted much attention as potential candidates for use in bone implants. In this paper, the MgZn/HA composites were prepared using powder metallurgy (PM) and the merging mechanism of MgZn and HA particles was investigated by adjusting the weight ratio of the HA powder. The evolution of the HA distribution in the matrix was examined using SEM and micro-CT images. Afterward, the mechanical properties and biocompatibility of the composites were discussed in detail. The results revealed that the mechanical properties and biocompatibility of the Mg-Zn/HA composites were significantly affected by the HA content. Composites with a low HA content showed increased porosity, improved mechanical strength, and enhanced corrosion resistance after ball milling and cold pressing. These results underscore the importance of optimizing the HA content in Mg-Zn/HA composites for bone implants. Based on our findings, PM Mg-Zn/HA composites with a moderate HA content demonstrate the most promising characteristics as bone implants. The insights gained from this work contribute to the advancement of bone implant materials and hold great potential for enhancing orthopedic surgery outcomes.