Developing Improved Mechanical Property and Corrosion Resistance of Mg-9Li Alloy via Solid-Solution Treatment

Abstract

Cast Mg-9Li alloy was successfully solid-solution (SS) treated via heating at 575 °C for 4.5 h and rapidly quenched with ice-water mixture. The mechanical property and corrosion resistance of the SS alloy were simultaneously improved. Rapid bcc/hcp phase transition of the alloy occurred during the quenching process, creating the newly precipitated needle-like fine α-Mg phase, uniformly distributed in the β-Li phase matrix. Dramatic grain refinement and uniform distribution of the α-Mg phase, as well as the massively increased α/β phase interfaces, are factors leading to the improved mechanical property of the SS alloy. Meanwhile, due to the modified duplex-phase structure, the SS alloy has a uniform corrosion-resistant surface film on the β-Li phase, which completely covers the entire alloy surface and efficiently protects the substrate. In addition, the SS alloy has fewer difference in the elements concentration and corrosion activity of the duplex phases, which reduces the pitting sensitivity and improves the corrosion resistance of the alloy matrix. The findings in this binary Mg-Li alloy can also serve as a benchmark for other more practical and complicated Mg-Li alloys.

Dual-Layer Corrosion-Resistant Conversion Coatings on Mg-9Li Alloy via Hydrothermal Synthesis in Deionized Water

“…It is apparent that the Mg-9Li alloy exhibits a typical dual-phase structure, which includes the bright lath phase and dark matrix phase. It is well known that the bright lath phase is the Mg-enriched α phase with hcp structure, which is a solution of lithium in magnesium and usually named as α-Mg phase [31]. The dark matrix phase surrounding the α-Mg phase is briefly named as β-Li phase, which is a solution of magnesium in lithium and shows a bcc structure [32].…”

Forming and Heat Treatment of Modern Metallic Materials

“…The second group consists of contributions devoted to shaping and unconventional shaping [5][6][7]. The third group includes those articles that deal with the field of heat treatment [8][9][10][11][12][13]. Perhaps the contributions could be divided in other ways, but we consider this appropriate.…”

“…The mechanical property and corrosion resistance of the SS alloy were simultaneously improved. Rapid bcc/hcp phase transition of the alloy occurred during the quenching process, creating the newly precipitated needle-like fine α-Mg phase, uniformly distributed in the β-Li phase matrix [12]. The dimension quality of the strip within the hardening process is an essential parameter, which needs to be paid great attention to.…”

“…The Mg-9Li alloy was worked up to solid solution (SS) for 4.5 h by heating to 575 • C and rapidly decomposed with a mixture of ice and water by Wang et al [12]. At the same time, the mechanical properties and corrosion resistance of the SS alloy were improved.…”

Effect of Heat Treatment on Low‐Cycle Fatigue Performance of LZ91 Mg–Li Alloy

“…Solution treatment of the Mg–9Li alloy at 1067 K for 4.5 h increased its yield strength from 62 to 110 MPa; the UTS increased from 100 to 120 MPa, and elongation increased from 32% to 45%. [ 15 ] Liu et al [ 16 ] used T6 state Mg–Y–Nd–Zr alloys obtained via solution and aging treatments under two different sets of conditions (T6 0 solution at 977 K for 4 h and aging at 437 K for 34 h; T6 1 solution at 968 K for 8 h and aging at 437 K for 16 h) and demonstrated that heat treatment can effectively improve the low‐cycle fatigue life of the Mg alloy. Zhang et al [ 17 ] found that aging treatment and the combination of solution and aging treatment improved the cyclic deformation resistance of hot extruded Mg–7%Zn–0.6%Zr–0.5%Y, aging treatment reduced the fatigue life of the alloy, and the combination of solid solution and aging treatment improved the alloy fatigue life under higher total applied strain amplitude; however, it reduced the low‐cycle fatigue life of the alloy under lower total applied strain amplitude.…”