Effect of the LPSO volume fraction on the microstructure and mechanical properties of Mg–Y2X –Zn X alloys

Abstract

The influence of the volume fraction of Long Period Stacking Ordered structure (LPSO) on the microstructure and mechanical properties in three extruded Mg 100-3x Y 2x Zn x alloys (x = 0.5, 1 and 1.5 at.%) has been studied. Two structures of LPSO-phase coexist in these extruded alloys, 18R and 14H. The 18R structure transforms to 14H structure gradually in the course of the extrusion process. For the three alloys, the grain size in the vicinity of LPSO-phase particles is refined due to a Particle Stimulated Nucleation mechanism (PSN). The reinforcing effect of the LPSO phase is active up to 523 K. Above this temperature, grain size effect becomes important. Accordingly, MgY 1 Zn 0,5 extruded alloy shows the highest mechanical strength above 523 K.

Characterization of Microstructure and Mechanical Properties of Mg–Y–Zn Alloys with Respect to Different Content of LPSO Phase

“…Similar results were presented by Oñorbe et al, where they show that a particle-stimulated nucleation (PSN) process can control the recrystallization process in LPSO alloys. [20] The volume fraction of the recrystallized grains in all investigated Mg alloys is almost constant. The change in the size of the recrystallized grains is also negligible within the investigated alloys.…”

Microstructures of Long-Period Stacking Ordered Phase of Mg–Zn–Y Alloy

“…It was reported that the fine dispersion of intermetallic second-phases with the addition of yttrium improves the mechanical strength of the MgZnY alloy at both room and high temperatures. 11,12) To date, second phases observed around kink boundaries have been determined to be three kinds of intermetallic compounds: MgZnY, MgZn and MgY with hexagonal structures, and they are considered to have higher hardness than the LPSO matrix.…”

Non-Basal Slip Systems Operative in Mg₁₂ZnY Long-Period Stacking Ordered (LPSO) Phase with 18R and 14H Structures

“…1416) In addition, this alloy has a high potential for application as a high-temperature structural alloy because the strength remains very high at least up to 200°C. 15,21,22) The mechanical properties of a Mg 89 Zn 4 Y 7 (at%) extruded alloy containing the LPSO phase of more than 85 vol% were also examined, and we clarified that the alloy shows an extremely high yield stress of ³480 MPa at RT. 23) Therefore, there is a strong possibility that the high-volume-fraction LPSO phase alloys could be used in structural materials requiring an extremely high strength/weight ratio.…”