(1. 鄭州輕研合金科技有限公司，鄭州 450041；
2. 鄭州大學(xué)材料科學(xué)與工程學(xué)院，鄭州 450001；
3. 隆基樂葉光伏科技有限公司，西安 710000)
摘 要: 采用鑄造、擠壓、冷軋和退火的方法，獲得了雙相LZ91鎂鋰合金板材，并通過OM、SEM、TEM和拉伸實驗，研究了雙相LZ91鎂鋰合金板材在200~300 ℃、應(yīng)變速率1.0×10-2~1.7×10-4 s-1條件下的超塑性變形行為、顯微組織演變和空洞長大機制。結(jié)果表明：雙相LZ91鎂鋰合金在285 ℃、1.7×10-4 s-1條件下的最大超塑性達到485%；拉伸過程中微觀組織由初始的β-Li再結(jié)晶相和α-Mg條帶狀相向等軸的β-Li相、α-Mg再結(jié)晶相以及β-Li基體中的次生α-Mg納米相進行演變；空洞主要形核于α/β兩相晶界處，變形早期在應(yīng)力作用下，空洞沿著晶界擴散長大，是擴散控制的長大機制；變形后期在周圍材料的塑性變形作用下，空洞被拉伸長大，是塑性變形控制的長大機制。
關(guān)鍵字: 雙相LZ91鎂鋰合金；超塑性；空洞；顯微組織演化
（1. Zhengzhou Light Alloy Institute Co., Ltd., Zhengzhou 450041,
China;
2. School of Materials Science and Engineering,
Zhengzhou University, Zhengzhou 450001, China;
3. LONGi Solar Technology Co., Ltd., Xi’an 710000,
China）
Abstract:The dual-phase LZ91 alloy plate was prepared by vacuum casting, extrusion, cold rolling and annealing. The superplastic behavior, microstructure evolution and cavity growth mechanism of LZ91 Mg-Li alloy were investigated using OM, SEM, TEM and tensile tests in the temperature range 200 ℃ to 300 ℃ and strain rate of 1.0×10-2 s-1 to1.7×10-4 s-1. The results show that the maximum superplasticity of dual-phase LZ91 Mg-Li alloy reaches 485% at 285 ℃, 1.7×10-4 s-1. During the superplastic deformation, the microstructure evolves from initial β-Li recrystallized phase and banded α-Mg phase to equiaxial β-Li phase, α-Mg recrystallized phase and nano α-Mg precipitates in β-Li matrix. The cavitation is mainly nucleated at the α/β interface. In the early stage of deformation, the cavity diffuses and grows along the grain boundary due to the promotion of stress, which is the diffusion-controlled growth mechanism. While, the cavity is stretched under the plastic deformation of the surrounding material in the later stage of deformation, then the growth mechanism is plastic deformation-controlled.
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