熱機處理對MgLiAlZn合金機械性質之影響

Influence of TMT on Mechanical Properties of MgLiAlZn Alloys

王建義(Jian-Yih Wang) ； 徐章銓(Chang-Chuan Hsu) ； 楊思誠(Sy-Cherng Yang)

《興大工程學刊》 22卷2期 (2011/08) Pp. 65-76

https://doi.org/10.6287/JENCHU.2011.2202.02

摘要

MgLi系合金具有優異室溫成形性，但其機械性質比一般鎂合金差。室溫軋延對擠製MgLiAlZn合金之加工硬化效果不大，主要是因MgLiAlZn基地β相產生再結晶及應力促使粗大α相析出所致。充分固溶後能有效抑制再結晶及α相析出之效果，因此固溶再室溫軋延達90%時，由於固溶強化與加工強化之雙重效果，使抗拉強度高達276 MPa，而伸長率仍有20%，顯示MgLiAlZn合金經固溶再室溫軋延可獲得高強度與高延性。此合金之自然時效處理，48 h即達尖峰時效，此時係析出寬2-3 nm長約10 nm的桿狀pre-θ相。時效時間越長，隨著θ相形成，同時有α相析出。但是粗大α相之析出對其機械性質提升並無貢獻。

關鍵字

鎂鋰合金 ； 時效 ； 析出 ； 加工硬化

並列摘要

MgLi series alloys have excellent formability at room temperature, but their mechanical properties are worse than general magnesium alloys. The effect of work hardening is little for the rolling at room temperature of the extruded MgLiAlZn alloy, mainly because β matrix phase generates recrystallization and the stress promotes the precipitation of coarse α phase. Therefore, the 90% reduction in rolling after the solid solution treatment, due to the effects of both solid solution strengthening and work hardening, the tensile strength and elongation are 276 MPa and 20% respectively. This shows the rolling of MgLiAlZn alloy after solid solution treatment can obtain high strength and high ductility.For the natural aging treatment of this alloy, peak aging reaches at 48hrs and precipitates the pellet shape pre-θ phase of 2-3 nm wide and about 10nm long. The longer the aging time, the pre-θ phase disappears, θ phase forms and α phase precipitates at the same time. However, precipitation of coarser α phase at a longer time has no contribution to enhance its mechanical properties.

並列關鍵字

magnesium-lithium alloy ； aging ； precipitation ； work hardening