Corrosion Behaviors of Long‐Period Stacking Ordered Structure in Mg Alloys Used in Biomaterials: A Review

Abstract

The long‐period stacking ordered (LPSO) phases have distinctive microstructures and significant effect on the promotion of mechanical properties of Mg alloys, which have received considerable attention not only as industrial materials but also as biodegradable implant materials recently. By now, numerous researchers devote to study the effects of the microstructures of LPSO phases on the mechanical properties of Mg alloys. But a few of them reveal the relationship between LPSO phases and corrosion behaviors of Mg alloys. Therefore, the knowledge of characteristics of LPSO phases and their effects on biocorrosion behaviors is essential. In this review, the current understanding about the structure, growth, transformation, and deformation of LPSO phases in Mg alloys are summarized. The recent developments of biocorrosion behaviors of Mg alloys are reviewed. The information on the immersion and corrosion mechanisms of Mg alloys are provided. The role of LPSO structures on corrosion behaviors of Mg alloys is intensively analyzed. Based on the current understandings, some problems are pointed out and suggestions for further research of Mg alloys with LPSO structures using as biomedical materials are provided.

Multimodal Microstructure and Mechanical Properties of AZ91 Mg Alloy Prepared by Equal Channel Angular Pressing plus Aging

“…As the lightest structural metal on earth, magnesium has obvious advantages of rich resource, ease of recycling, and good biocompatibility [1][2][3]. These unique properties make magnesium and its alloys attractive for automotive, aerospace, and biomedical applications.…”

Effect of Microalloyed Al on Microstructure and Corrosion Behaviors of As‐Cast Mg–Zn–Y–Mn Alloys

“…The EDS (Figure 1f–h) and XRD patterns ( Figure ) revealed that the block shape phase was 18R–LPSO phase (Mg 12 YZn) and the eutectic structure was W phase (Mg 3 Zn 3 Y 2 ), which was agreed with the phase diagram [ 29 ] and previous reports. [ 27,28 ] X‐ray phase analysis showed that when Al was added to the based alloy, a new diffraction peak emerged, which was named as Al(Y, Zn) in this article according to EDS results (Figure 1h and Figure 5). The EDS results showed that the new phase was rich in Al, Zn, and Y element.…”

“…[ 28 ] Hydrogen evolution experiment was to collect hydrogen (H 2 ) produced during the reaction into the burette above the samples. The average corrosion rates from mass loss ( P w mm/y) and hydrogen evolution ( P AH mm/y) were calculated by following equations [ 28 ] where W (mg) was the weight before immersion and W 0 (mg) was the weight after removing corrosion products. t 1 and t 2 were the immersion time ( t 1 = t 2 , days) and the area exposed to the solution ( A 1 = A 2 , cm 2 ).…”

Enhanced Performance of Mg–Zn–Y–Mn Alloy via Minor Ca Addition

“…In general, by adjusting the Zn/Y atomic ratio, three kinds of ternary equilibrium phases can be obtained in the Mg–Zn–Y alloys, namely, LPSO phase, I phase, and W phase . Among them, LPSO phase is an excellent strengthening phase which is tightly combined with the α‐Mg matrix and could effectively improve the mechanical and corrosion properties . There are various methods for improving the performance of Mg–Zn–Y alloys containing LPSO, such as the production of new alloys by introducing alloying elements (Zr, Sr, B, Ti, and Mn) or ceramic particles (B 4 C and TiB 2 ), various novel casting methods by ultrasonic and electromagnetic stirring treatment, and grain refinement by severe plastic deformation (hot extrusion, rolling, and equal channel angular pressing) .…”