Mg and Its Alloys for Biomedical Applications: Exploring Corrosion and Its Interplay with Mechanical Failure

Abstract

Abstract:The future of biomaterial design will rely on temporary implant materials that degrade while tissues grow, releasing no toxic species during degradation and no residue after full regeneration of the targeted anatomic site. In this aspect, Mg and its alloys are receiving increasing attention because they allow both mechanical strength and biodegradability. Yet their use as biomedical implants is limited due to their poor corrosion resistance and the consequential mechanical integrity problems leading to corrosion assisted cracking. This review provides the reader with an overview of current biomaterials, their stringent mechanical and chemical requirements and the potential of Mg alloys to fulfil them. We provide insight into corrosion mechanisms of Mg and its alloys, the fundamentals and established models behind stress corrosion cracking and corrosion fatigue. We explain Mgs unique negative differential effect and approaches to describe it. Finally, we go into depth on corrosion improvements, reviewing literature on high purity Mg, on the effect of alloying elements and their tolerance levels, as well as research on surface treatments that allow to tune degradation kinetics. Bridging fundamentals aspects with current research activities in the field, this review intends to give a substantial overview for all interested readers; potential and current researchers and practitioners of the future not yet familiar with this promising material.

Grain Size-Related Strengthening and Softening of a Precompressed and Heat-Treated Mg–Zn–Ca Alloy

“…Interestingly, after processing the alloy, the yield strength is higher in compression rather than in tension [10]. Similar mechanical properties are observed in natural bones, where CYS is found to be around 130-180 MPa, TYS varied between 80 and 150 MPa, and elongation to failure is 1%-7% [3]. Thus, the proposed processing seems to be useful for the production of the next generation of biomedical materials.…”

“…The Mg-Zn-Ca alloys belong to the prospective metallic biomaterials due to their biocompatibility, biodegradability [1,2] and the Young's modulus of the alloys being close to that of bones [3]. A low amount of alloying elements reduces production costs, and thus increases economic efficiency.…”

Cycle numbers to failure for magnesium and its alloys in human body fluid

“…In Table 1 (Peron et al, 2017), mechanical properties of natural bone and Magnesium are indicated. With a quick review of the mechanical properties of natural bone and Magnesium, it can be concluded that the values of the material properties of natural bone and Magnesium are close to each other.…”

Microstructure, corrosion behavior, and surface mechanical properties of Fe oxide coatings on biomedical ZK60 Mg alloy

“…In addition, their nontoxic degradation products of Mg hydroxides can stimulate osteoblast activity and promote the regeneration of new bone . However, Mg alloys usually lose structural integrity in early implantation stage because of the poor corrosion resistance and thus fail to provide mechanical strength during the tissue repair process, which remains the main restriction for their clinical applications …”