Effect of substitution of 1 at% Ni for Zn on the microstructure and mechanical properties of Mg94Y4Zn2 alloy
Effect of substitution of 1 at% Ni for Zn on the microstructure and mechanical properties of Mg94Y4Zn2 alloy
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DOI：
10.1016/j.msea.2013.07.036
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发表时间：
2013-11
期刊：
影响因子：
6.4
通讯作者：
Hua-nan Liu;F. Xue;J. Bai;Jian Zhou;Xiaodao Liu
中科院分区：
文献类型：
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作者：
Hua-nan Liu;F. Xue;J. Bai;Jian Zhou;Xiaodao Liu
利用光学显微镜、扫描电子显微镜、透射电子显微镜和电子万能试验机系统地研究了镁94Y4Zn2和镁94Y4Zn1Ni1合金的显微组织和力学性能。铸态WZ42合金由α-Mg基体、18RLPSO(长周期有序堆积)相和少量的Mg_(24)(Y，Zn)_5相组成。取代1at%Ni原子后，WZN411合金的相结构保持不变，但化学成分发生了明显变化。α-Mg合金中存在大量的层错，而WZN411合金中几乎没有观察到层错。在500℃保温12h后，WZ42合金中形成了大量的14HLPSO片层，并在18R相间生成了许多纳米级的α-Mg片层。相反，WZN411合金中的18R是热稳定的，退火后α-Mg片层的形成和14H片层的形成都受到限制。拉伸试验表明，挤压后的WZ42合金室温极限抗拉强度为390℃，屈服强度为246℃，伸长率为2.8%。WZN411合金中添加1at%Ni后，其抗拉强度和抗弯强度提高了20℃，塑性也有所改善。综合力学性能的改善可归因于1at%Ni元素的替代，它可以提高18R相的固溶强化程度，并刺激18R相在退火和挤压过程中的热稳定性。
The microstructure and mechanical properties of Mg94Y4Zn2and Mg94Y4Zn1Ni1alloys have been systematically investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and an electronic universal testing machine. The as-cast WZ42 alloy is composed of α-Mg matrix, 18R LPSO (long period stacking ordered) phase and a small fraction of Mg24(Y,Zn)5phases. With the replacement of 1 at% Ni atoms, the phase structures in WZN411 alloy remain unchanged, but their chemical compositions vary obviously. A great number of stacking faults exist in α-Mg grains of WZ42 alloy, while they are barely observed in WZN411 alloy. After annealing at 500 °C for 12 h, there are plenty of 14H LPSO lamellas formed in WZ42 alloy and many nano-scale α-Mg slices generated between 18R phases. In contrast, the 18R in WZN411 alloy is thermally stable, and both the formation of α-Mg slices and 14H lamellas are restricted for annealed WZN411 alloy. Tensile tests indicate that the as-extruded WZ42 alloy exhibits ultimate tensile strength of 390 MPa, tensile yield strength of 246 MPa and elongation of 2.8% at room temperature. With the replacement of 1 at% Ni, the UTS and TYS of WZN411 alloy increase by 20 MPa and the ductility improves as well. The improvement of comprehensive mechanical properties could be ascribed to the substitution of 1 at% Ni element, which could enhance the degree of solid-solution strengthening and stimulate the thermal stability of 18R phase during annealing and extrusion processes.