(1. 郑州轻研合金科技有限公司，郑州 450041；
2. 郑州大学材料科学与工程学院，郑州 450001；
3. 隆基乐叶光伏科技有限公司，西安 710000)
摘 要: 采用铸造、挤压、冷轧和退火的方法，获得了双相LZ91镁锂合金板材，并通过OM、SEM、TEM和拉伸实验，研究了双相LZ91镁锂合金板材在200~300 ℃、应变速率1.0×10-2~1.7×10-4 s-1条件下的超塑性变形行为、显微组织演变和空洞长大机制。结果表明：双相LZ91镁锂合金在285 ℃、1.7×10-4 s-1条件下的最大超塑性达到485%；拉伸过程中微观组织由初始的β-Li再结晶相和α-Mg条带状相向等轴的β-Li相、α-Mg再结晶相以及β-Li基体中的次生α-Mg纳米相进行演变；空洞主要形核于α/β两相晶界处，变形早期在应力作用下，空洞沿着晶界扩散长大，是扩散控制的长大机制；变形后期在周围材料的塑性变形作用下，空洞被拉伸长大，是塑性变形控制的长大机制。
关键字: 双相LZ91镁锂合金；超塑性；空洞；显微组织演化
（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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