Influence of Coarse Mg3Bi2 Particles on Deformation Behaviors of Mg-Bi Alloys

Abstract

Mg-Bi binary alloys with concentrations of 1, 3, 6, and 9 wt% Bi and ternary Mg-9Bi-2.5Zn alloy were prepared by casting and hot extrusion. The results show that alloying with Bi refined as-cast grains of Mg alloys and the refinement efficiency of Bi is in between Al and Zr. It was also found that a critical value for the area fraction of constituent Mg3Bi2 particles seems to appear, which influences the dynamic recrystallization mechanism during extrusion. This influence results in either uniform or heterogenetic distribution of grain size and different extrusion texture intensities. Furthermore, the addition of Zn affected both the grain size and the area fraction/size of Mg3Bi2. Mechanical results and microstructure/fractography observation suggest that Mg3Bi2 particles do not impact the tensile nor compression yielding stress but act as fracture sources.

Effects of Bi–Sn–Pb Alloy and Ball-Milling Duration on the Reactivity of Magnesium–Aluminum Waste-Based Materials for Hydrogen Production

“…The formation of the new compounds (and the absence of the original alloy phases in the samples) supported the version that the Rose alloy melted during ball milling and its components reacted with Mg. The existence of Mg 2 Pb, Mg 2 Sn, and Mg 3 Bi 2 was confirmed for a number of Mg-based alloys [ 123 , 124 , 125 ]. The samples ball milled with smaller amounts of additive differed from those with larger ones in that their peaks for the new phases were lower.…”

“…In case of the AZ91 modified with Ca and Bi (1 wt.%), no corrosion was observed in the Mg 2 Ca phase while Mg 3 Bi 2 sites were exposed to severe attack [ 155 ]. The introduction of 0.5 wt.% Bi into the Mg–1.2Ca system was reported to increase its protection against corrosion, while the larger tested values of 1.5, 3, 5, and 12 wt.% diminished it; for the concentrations of 3 wt.% and higher, a significant reduction in the grain size and enhanced dynamic recrystallization of the matrix were established as well [ 123 , 156 , 157 ]. In study [ 158 ], for the tested Mg–Bi alloys the self-discharge rates associated with hydrogen evolution were the lowest for 0.5 wt.% and gradually increased for 1 and 2 wt.%.…”