摘要
通过金相观察(OM)、扫描电镜观察(SEM)、能谱分析(EDS)、拉伸试验研究了Gd元素含量对砂型铸造Mg-Gd-Y系合金微观组织和力学性能的影响,并引入WE54合金作为对比。研究表明:Mg-Gd-Y系合金的铸态组织主要由等轴树枝晶α-Mg固溶体、晶界处孤岛状共晶相Mg24(Gd,Y)5以及孤立的方块相Mg5(Gd,Y)和起到晶粒细化作用的富Zr核心组成。随着Gd含量的增加,晶界处第二相Mg24(Gd,Y)5的体积分数明显增加,导致合金的抗拉强度和屈服强度不断提高,伸长率却不断降低。GW94合金强度最好:室温下抗拉强度和屈服强度最高分别可达213.7 MPa和156 MPa,伸长率却仅为1.29%。WE54合金的伸长率最高,这可能与铸态WE54合金晶界处形成的相互平行的片层状共晶相有关。Mg-Gd-Y系合金和WE54合金断裂机制都为准解理断裂。
Abstract： The microstructure and mechanical properties of sand casting Mg-Gd-Y system alloys were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, energy dispersive spectrometer （EDS） and tensile tests, and the WE54 Mg alloy was also introduced as a comparison. The results show that the microstructure of as-cast Mg-Gd-Y system alloys were mainly composed of equiaxed dendrite of α-Mg solid solution, isolated island-like eutectic phase of Mg24（Gd,Y）5 at the grain boundaries, isolated square particles of Mgs（Gd,Y） and Zr-rich core playing a role in grain refinement. As the content of Gd addition to Mg-Gd-Y alloy increased, the ultimate tensile strength and yield strength increased gradually, while the elongation reduced gradually. The strength improvement was attributed to increase of the volume fraction of Mg2a（Gd,Y）5 at the grain boundaries. The strength of GW94 alloy was highest in present four alloys, and the tensile strength, yield strength and elongation at room temperature was 213.7 MPa, 156 MPa and 1.29%, respectively. The elongation of WE54 alloy was the highest, which may be due to its lamellar eutectic phase at the grain boundaries. The fracture modes of Mg-Gd-Y alloy and WE54 Mg alloy were both quasi-cleavage fracture.
出处
《铸造》
CAS
CSCD
北大核心
2015年第9期887-892,共6页
Foundry
基金
国家重点基础研究发展计划(973计划:2013CB632202)
国家自然科学基金(51301173)
作者简介
杨庆波（1987-），男，硕士生，研究方向为高强耐热Mg—Gd—Y合金微观组织和力学性能。E—mail：813351739@qq．com
通讯作者：吴迪，男，副研究员，博士。E—mail：dwu@imr．ac．cn
