Effect of Heat Treatment on the Mechanical and Corrosion Properties of Mg–Zn–Ga Biodegradable Mg Alloys

Abstract

Mg alloys have mechanical properties similar to those of human bones, and have been studied extensively because of their potential use in biodegradable medical implants. In this study, the influence of different heat treatment regimens on the microstructure and mechanical and corrosion properties of biodegradable Mg–Zn–Ga alloys was investigated, because Ga is effective in the treatment of disorders associated with accelerated bone loss. Solid–solution heat treatment (SSHT) enhanced the mechanical properties of these alloys, and a low corrosion rate in Hanks’ solution was achieved because of the decrease in the cathodic-phase content after SSHT. Thus, the Mg–4 wt.% Zn–4 wt.% Ga–0.5 wt.% Y alloy after 18 h of SSHT at 350 °C (ultimate tensile strength: 207 MPa; yield strength: 97 MPa; elongation at fracture: 7.5%; corrosion rate: 0.27 mm/year) was recommended for low-loaded orthopedic implants.

Microstructure and Mechanical Properties of Hot-Extruded Mg–Zn–Ga–(Y) Biodegradable Alloys

“…In previous work, it was shown that the solution heat treatment of the Mg–Zn–Ga–(Y) alloys induced a high El (up to 15.2%) and produced a low fraction of intermetallic phases that provided high corrosion resistance [ 36 ]. However, aging had a low effect on the alloy strength and still has a low value.…”

“…For melt protection from ignition, an Ar + 2 vol.% SF 6 protective atmosphere was used. The details of the melting procedure can be found elsewhere [ 36 ]. Cylindrical ingots with a diameter of 60 mm and a length of 200 mm were cast into an aluminum permanent mold preheated to 150 °C.…”

Natural Coatings and Surface Modifications on Magnesium Alloys for Biomedical Applications

“…In addition, some elements, such as beryllium and nickel, should be strictly controlled and even avoided as they may potentially cause adverse effects on the human body [ 24 ]. Heat treatment strategies and their influence on the corrosion properties of Mg–Zn–Ga alloys have been studied to investigate their usefulness for osteosynthesis applications, with promising results, such as a low corrosion rate and good mechanical properties [ 25 ]. Other techniques, such as surface modification and coatings with ceramic, polymeric, and hybrid materials, are effective in controlling the degradation rate of Mg [ 26 ].…”

Bone Remodeling Interaction with Magnesium Alloy Implants Studied by SEM and EDX

“…Mg alloys can obtain considerable mechanical properties upon Zn and Ga additions after deformation processing [ 17 , 18 , 19 ]. Ga’s effectiveness in treating disorders associated with accelerated bone loss, and its antibacterial properties, underline the potential of Ga as an alloying element for biodegradable Mg alloys [ 20 , 21 , 22 , 23 , 24 ].…”