Effects of Li on Microstructures, Mechanical, and Biocorrosion Properties of Biodegradable Mg_94‐xZn₂Y₄Li_x Alloys with Long Period Stacking Ordered Phase

Abstract

Mg 94-x Zn 2 Y 4 Li x alloys (at%) (x ¼ 0, 1, 5, 9, 13) are designed to develop a novel, biodegradable magnesium alloy. Microstructures evolution and mechanical properties are evaluated by using OM, XRD, SEM, and tensile tests. The biocorrosion behaviors of the alloys are investigated by using hydrogen evolution and electrochemical measurements. The precipitation of 18R LPSO phase is facilitated by a little Li (<1 at%), while exceeded Li (>1 at%) inhibits the formation of 18R LPSO phase and favors the formation of (Mg,Zn) 24 Y 5 eutectic phase. The grain size of a-Mg phase is refined with 5 at% Li. Besides the optimal combined mechanical properties (UTS ¼ 190 MPa, elongation ¼ 3.1%), the as-cast Mg 89 Zn 2 Y 4 Li 5 alloy has the lowest corrosion rate and the highest biocorrosion resistance, which are desirable for use as a biomaterial.

Corrosion Inhibition of AZ31-xLi (x = 4, 8, 12) Magnesium Alloys in Sodium Chloride Solutions by Aqueous Molybdate

“…An increase in the volume fraction of the Li-containing IMPs promotes filiform corrosion along the grain boundaries and inside the β-Li phase [35]. An increase in the corrosion rate with increasing amounts of Li was reported for Mg-Al-Li, Mg-Zn-Li, Mg-Li-Al-Zn-Y, Mg-Li-Ca, and Mg-Al-Li-Zn alloys [24,26,28,36].…”

“…The effect of Li concentration on the corrosion resistance of Mg alloys, additionally containing other alloying elements is not so straightforward [16,[24][25][26][27][28][29][30]. Common Mg alloys have various types of intermetallic particles (IMPs) in their microstructure, most of them being cathodic relative to the alloy matrix [16,31,32].…”

The Promise of Mg-Li Based Alloys for Biomedical Implant Materials

“…The ability of long period stacking ordered (LPSO) phase to enhance mechanical properties has also been investigated [47]. The addition of >1 at.…”

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

“…[ 17,18 ] Some researches had reported that LPSO phase can be corrosion barriers to inhibit further corrosion. [ 19,20 ] However, LPSO phase can also act as a local cathode to accelerate corrosion. [ 21 ] This beneficial or detrimental effect may be achieved by the second phases, with varying chemical composition and microstructure.…”

“…[ 22 ] Alloying treatment is an efficient approach to restrict grain growth and to control small second phase at grain boundaries during solidification. [ 23 ] Therefore, there were an increasing number of researches about alloying element, such as Li [ 19 ] and Mn. [ 20 ]…”