Fundamentals and advances in magnesium alloy corrosion

Magnesium (Mg(2+)) is an essential ion to the human body, playing an instrumental role in supporting and sustaining health and life. As the second most abundant intracellular cation after potassium, it is involved in over 600 enzymatic reactions including energy metabolism and protein synthesis. Although Mg(2+) availability has been proven to be disturbed during several clinical situations, serum Mg(2+) values are not generally determined in patients. This review aims to provide an overview of the function of Mg(2+) in human health and disease. In short, Mg(2+) plays an important physiological role particularly in the brain, heart, and skeletal muscles. Moreover, Mg(2+) supplementation has been shown to be beneficial in treatment of, among others, preeclampsia, migraine, depression, coronary artery disease, and asthma. Over the last decade, several hereditary forms of hypomagnesemia have been deciphered, including mutations in transient receptor potential melastatin type 6 (TRPM6), claudin 16, and cyclin M2 (CNNM2). Recently, mutations in Mg(2+) transporter 1 (MagT1) were linked to T-cell deficiency underlining the important role of Mg(2+) in cell viability. Moreover, hypomagnesemia can be the consequence of the use of certain types of drugs, such as diuretics, epidermal growth factor receptor inhibitors, calcineurin inhibitors, and proton pump inhibitors. This review provides an extensive and comprehensive overview of Mg(2+) research over the last few decades, focusing on the regulation of Mg(2+) homeostasis in the intestine, kidney, and bone and disturbances which may result in hypomagnesemia.

Magnesium in Man: Implications for Health and Disease

Corrosion behaviour of magnesium/aluminium alloys in 3.5 wt.% NaCl

Magnesium (Mg) has garnered significant interest for its potential use as a biodegradable implant material. Of specific interest in this study is the effect of zinc (Zn) and strontium (Sr) additions on both the mechanical and degradation behaviors in Mg due to their established beneficial effect on strength and microstructural grain refinement while being biocompatible. Three binary Mg-x wt% Sr (x=0.5, 1.0, 1.5) alloys and three ternary Mg-x wt%Zn-0.5 wt% Sr (x=2.0, 4.0, 6.0) were studied to evaluate their mechanical and degradation behavior. Mechanical testing was performed at room temperature on solution-treated and peak aged alloys using microhardness and tensile tests. Degradation was studied using immersion tests in Hanks' solution. Results indicate a decrease in grain size and an increase in strength with increasing Sr and Zn content. When considering degradation behavior Mg-0.5 wt%Sr demonstrated the lowest degradation rate among binary alloys. At constant Sr content at 0.5 wt%, the addition of Zn increased the corrosion rate, with the highest rate for the Mg-6.0 wt%Zn-0.5 wt%Sr. The alloys which best optimized both mechanical and degradation behaviors were Mg-2.0 wt%Zn-0.5 wt%Sr and Mg-4.0 wt%Zn-0.5 wt%Sr. Finally, microstructure and property relationships were evaluated and discussed in reference to each alloy's potential use as a biodegradable implant material.

Investigation of the mechanical and degradation properties of Mg-Sr and Mg-Zn-Sr alloys for use as potential biodegradable implant materials.

Deformation twinning in AZ31: Influence on strain hardening and texture evolution

Magnesium is the lightest of all metals used as the basis for constructional alloys. It is this property which entices automobile manufacturers to replace denser materials, not only steels, cast irons and copper base alloys but even aluminium alloys by magnesium based alloys. The requirement to reduce the weight of car components as a result in part of the introduction of legislation limiting emission has triggered renewed interest in magnesium. The growth rate over the next 10 years has been forecast to be 7% per annum. A wider use of magnesium base alloys necessitates several parallel programs. These can be classified as alloy development, process development/improvement and design considerations. These will be discussed briefly and followed by some examples of the increasing uses of magnesium and future trends.

B.L Mordike

Papers

Magnesium: Properties — applications — potential