High-speed extrusion of dilute Mg-Zn-Ca-Mn alloys and its effect on microstructure, texture and mechanical properties
High-speed extrusion of dilute Mg-Zn-Ca-Mn alloys and its effect on microstructure, texture and mechanical properties
复制标题
稀Mg-Zn-Ca-Mn合金的高速挤压及其对组织、织构和力学性能的影响
DOI：
10.1016/j.msea.2016.10.007
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发表时间：
2016-12-15
期刊：
影响因子：
6.4
通讯作者：
Kamado, S.
中科院分区：
文献类型：
--
作者：
Jiang, M. G.;Xu, C.;Kamado, S.
在24 m/min的速度下成功挤压出3种Mg-Zn-Ca-Mn稀合金，其中锌含量最低（0.21 wt%）的合金甚至可以在60 m/min的速度下挤压出，表面没有任何缺陷，这归因于Mg2Ca相的热稳定和高固相温度（接近620℃）。在出模速度>= 6 m/min下挤压成形的合金在[2114]~[2112]平行挤压方向处呈现完全动态再结晶（DRXed）组织和弱稀土（RE）织构。在挤压过程中，细小的Mg2Ca和α - mn颗粒动态析出，通过齐纳阻力效应对DRXed晶粒生长起到有效的钉住障碍作用。由于变形温度随着挤压速度的增加而升高，晶粒尺寸逐渐增大，这可以从DRXed晶粒尺寸与Zener-Hollomon参数的关系来理解。RE织构对均匀伸长率的贡献接近23%，但晶粒尺寸的增加（bbb30 μ m）导致均匀变形后的伸长率下降，这是由于均匀变形后出现{10 (1)over bar1}和{10 (1)over bar1}-{10 (1) over bar2}双孪晶。
Three dilute Mg-Zn-Ca-Mn alloys were successfully extruded at 24 m/min and the alloy with lowest Zn content (0.21 wt%) can even be extruded at 60 m/min without any surface defects, which was ascribed to the thermally stable Mg2Ca phase and high solidus temperature (similar to 620 degrees C). The alloys extruded at die-exit speed >= 6 m/min showed a fully dynamically recrystallized (DRXed) microstructure and weak rare earth (RE) texture at the position between [2114] and [2112] parallel to the extrusion direction. Besides, fine Mg2Ca and alpha-Mn particles dynamically precipitated during extrusion, acting as effective pinning obstacles against the DRXed grain growth via Zener drag effect. Due to the deformation temperature rise with increasing extrusion speeds, the grain size increased gradually, which can be understood from the relationship between DRXed grain size and Zener-Hollomon parameter. The RE texture contributed to high uniform elongation of similar to 23%, but the increased grain size ( > 30 mu m) deteriorated post-uniform elongation due to the prevalence of {10 (1) over bar1} contraction and {10 (1) over bar1}-{10 (1) over bar2} double twins during post-uniform deformation.