Corrosion behavior and mechanical degradation of as‐extruded Mg–Gd–Zn–Zr alloys for orthopedic application

Abstract

The microstructures, corrosion behavior, and mechanical degradation of the as‐extruded Mg–6.0Gd–0.5Zn–0.4Zr (wt %, GZ60K) and Mg–6.0Gd–1.0Zn–0.4Zr (wt %, GZ61K) alloys were investigated. In both alloys, stacking faults and precipitates are formed in the recrystallized microstructures. The corrosion rate of GZ61K calculated by the hydrogen evolution in simulated body fluid is 0.34 ± 0.13 mm/year, which is lower than that of GZ60K (0.45 ± 0.09 mm/year); and the current density of GZ61K (5.23 ± 1.41 μA cm−2) is much lower than that of GZ60K (11.95 ± 3.37 μA cm−2). The corrosion results indicate GZ61K is more resistant to corrosion than GZ60K, but GZ60K presents more uniform corrosion mode as compared to GZ61K. After immersion in simulated body fluid for 7, 14, and 21 days, a slight decrease in the strength of both alloys is observed. The yield strength half‐life is assessed for mechanical degradation and determined to be 125 and 85 days for GZ60K and GZ61K, respectively. The as‐extruded GZ60K alloy with more uniform corrosion and longer mechanical integrity shows promising potential for orthopedic application.

Enhancement of mechanical properties and corrosion resistance of Mg–2Zn–0.5Zr–1.5Dy (mass%) alloy by a combination of heat treatment and hot extrusion

“…After immersion in SBF for 120 h, the corrosion products were removed using boiling chromic acid and silver nitrate solution. The corrosion rates of the alloys were calculated using the following equation [ 10 ] : where CR w is the corrosion rate calculated by mass loss (mm year −1 ), W is the mass loss after immersion (g), A is the area of the alloy (cm 2 ), ρ is the density of the alloy (g cm −3 ), and t 0 is the immersion time (h). SEM and EDS were used to observe and analyze the corrosion morphologies and products.…”

“…After immersion in SBF for 120 h, the corrosion products were removed using boiling chromic acid and silver nitrate solution. The corrosion rates of the alloys were calculated using the following equation [10] :…”

“…The factors limiting their clinical application can be summarized as follows: as orthopedic repair materials, their mechanical properties are poor in comparison to traditional materials such as stainless steels and titanium alloys, and they cannot withstand high loads [7] ; the corrosion rates of magnesium alloys are rapid and uncontrollable, and excess corrosion products are difficult for human tissue to absorb and they can easily cause tissue inflammation [4,8,9] ; local corrosion of magnesium alloys is a serious problem that will lead to rapid deterioration of their mechanical properties and reduce their service life. [3,10] Solving these issues is key to developing biodegradable magnesium alloys, and it is also the main direction of current research.…”

Effects of Gd and heat treatments on mechanical properties of Mg-xGd-1Zn-0.4Zr alloys

“…The mechanical properties have an important influence on the life of the magnesium alloy in the human body, especially for the load bearing. If the mechanical properties decay too fast, it will lead to premature failure of the implants [9]. Therefore, it is very important to study the mechanical behavior of biodegradable magnesium alloys.…”

Revealing the Microstructural Aspects of the Corrosion Dynamics in Rapidly Solidified Mg-Zn-Y Alloys Using the Acoustic Emission Technique

“…Some preliminary results on the investigation of corrosion of RS ribbon-consolidated Mg-Zn-Y alloys have been reported in [31,39,40]. More information about recent developments on the corrosion behaviors of Mg alloys with SFs or LPSO phase and their beneficial effect is provided in [41,42].…”