Ximei Zong

Effect of Precipitated Phases on Corrosion of Mg95.8Gd3Zn1Zr0.2 Alloy with Long-Period Stacking Ordered Structure

Abstract The microstructure of the precipitated phases of Mg95.8Gd3Zn1Zr0.2 alloys with long-period stacking ordered structure before and after heat treatment is discussed. The corrosion properties of the as-cast (F), solid-solution (T4) and aging-treated (T6) alloys in 1% NaCl solution are studied. The hydrogen evolution and electrochemical measurements display that the as-cast Mg95.8Gd3Zn1Zr0.2 alloy with the continuous network eutectic phase exhibits the greatest corrosion resistance, while T6 sample with some needle-like phases and the particle phases is the worst among the three alloys. It is proposed to be mainly related to the amount, composition, microstructure and distribution of the precipitated phases.

High-strength Mg95Y3Zn1Ni1 alloy with LPSO structure processed by hot rolling

ABSTRACT Microstructures and mechanical properties of Mg95Y3Zn1Ni1 alloy containing long period stacking ordered (LPSO) phase processed by hot rolling were systematically investigated in the present work. The results showed that the as-cast alloy was mainly composed of α-Mg and network 18 R LPSO phase. The thermal stability of 18 R LPSO phase in the as-cast alloys decreased with the decrease of Ni content. After solution treatment at 773 K for 40 h, network 18 R phase at grain boundary dissolved, while fine lamellar phase identified as 14H LPSO precipitated in the interior of grains. When the solid-solution alloy was hot rolled at 723 K with six passes and thickness reduction of 62%, some LPSO phases broke down and kinking of varying degrees occurred in LPSO phase. Meanwhile, the as-rolled α-Mg and LPSO phase redistributed aligned along the rolling orientation. The alloy exhibited excellent mechanical properties: yield strength of 282 MPa, ultimate tensile strength of 383 MPa, and elongation to failure of 16% at ambient temperature along the rolling orientation. The remarkable improvement of strength was ascribed to the refined microstructure induced by the deformation kinking and the crush of LPSO phase.

Microstructures and biocorrosion properties of biodegradable Mg–Zn–Y–Ca–xZr alloys

Abstract The influence of Zr microalloying on the microstructures and corrosion resistance of as-cast Mg-3.0Zn-0.6Y-0.3Ca (wt.%) alloy were investigated by means of optical microscopy, X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, immersion testing and electrochemical measurements. The results indicated that Zr induced the formation of a strip-like eutectic phase at the grain boundaries, and discouraged the formation of isolated particles. With the Zr addition, the microstructure was refined and the corrosion resistance was enhanced. The alloy with a Zr content of 0.5 wt.% has an optimal corrosion resistance, which can be attributed to the fine and continuously distributed strip-like I-phase and fine grain structure.