Increase in the Mechanical Strength of Mg-8Gd-3Y-1Zn Alloy Containing Long-Period Stacking Ordered Phases Using Equal Channel Angular Pressing Processing
Increase in the Mechanical Strength of Mg-8Gd-3Y-1Zn Alloy Containing Long-Period Stacking Ordered Phases Using Equal Channel Angular Pressing Processing
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DOI：
10.3390/met9020221
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发表时间：
2019-02
期刊：
影响因子：
2.9
通讯作者：
G. Garcés;P. Pérez;R. Barea;J. Medina;A. Stark;N. Schell;P. Adeva
中科院分区：
文献类型：
--
作者：
G. Garcés;P. Pérez;R. Barea;J. Medina;A. Stark;N. Schell;P. Adeva
研究了挤压态Mg-Gd-Y-Zn合金在等径角挤压过程中组织和性能的变化。挤压后，微观结构的特征在于镁基体内存在沿沿着伸长的长周期堆叠有序纤维。晶粒结构是随机取向的动态再结晶和粗的高度取向的非动态再结晶晶粒的混合物。在400 °C挤压后，稀土原子以固溶体形式存在，在200 °C热处理过程中，稀土原子发生沉淀。在基面上析出β'棱柱板和片状γ'，使拉伸屈服应力从325 MPa提高到409 MPa。在300 °C的等通道转角挤压过程中，动态再结晶晶粒的体积分数随着等通道转角挤压过程中引入的应变而连续增加。在ECAP处理的合金的晶界处同样观察到β相的析出。动态再结晶晶粒尺寸从挤压材料中的1.8 µm减小到ECAP合金中的0.5 µm。ECAP材料在200 °C下的热处理导致屈服应力增加至456 MPa，该屈服应力在200 °C下保持不变。
The evolution of the microstructure and mechanical properties during equal channel angular pressing processing has been studied in an extruded Mg-Gd-Y-Zn alloy containing long-period stacking ordered phases. After extrusion, the microstructure is characterized by the presence of long-period stacking ordered fibers elongated along the extrusion direction within the magnesium matrix. The grain structure is a mixture of randomly oriented dynamic recrystallized and coarse highly oriented non-dynamic recrystallized grains. Rare-earth atoms are in solid solution after extrusion at 400 °C and precipitation takes place during the thermal treatment at 200 °C. Precipitation of β’ prismatic plates and lamellar γ’ in the basal plane increases the tensile yield stress from 325 to 409 MPa. During equal channel angular pressing processing at 300 °C, the volume fraction of dynamic recrystallized grains continuously increases with the strain introduced during the equal channel angular pressing process. Precipitation of β phase is equally observed at grain boundaries of the ECAPed alloy. Dynamic recrystallized grain size decreases from 1.8 µm in the extruded material to 0.5 µm in the ECAPed alloy. Thermal treatment at 200 °C of ECAPed materials results in an increase of the yield stress up to 456 MPa, which is maintained up to 200 °C.