Effect of Equal-Channel Angular Pressing on the Structure and Properties of Fe–Mn–C Alloys for Biomedical Application

The possibility of producing alloys, which are characterized by high degradation rate and used for manufacturing biodegradable implants, is studied on Fe–Mn–C alloys subjected to equal-channel angular pressing (ECAP). In particular, the attention is paid to the preparation of alloys, which have an ultrafine-grained structure and a high density of boundaries of structural elements and are in completely austenitic state. The effect of a structure on the corrosion rate, the mechanical properties, and in vitro biocompatibility has been revealed. An analysis of X-ray diffraction and transmission electron microscopy data for the alloys subjected to ECAP shows the formation of an austenitic partially or completely twin structure. The formed structure determines a high level of the strength characteristics while maintaining an adequate plasticity. As the uniformity of the twin structure and density of twin packets increases and the twin size decreases, the corrosion rate is shown to decrease. Based on results of in vitro studies of the hemolytic efficiency and cytotoxicity, the biocompatibility of the alloys subjected to ECAP is retained. The treatment conditions of samples are found not to affect their biocompatibility and to ensure a similar level of the adherence of mesenchymal cells with an osteogenic potential on the surface of the alloy samples subjected to ECAP.