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研究了稀土元素Nd、Yb对Mg-5.5Zn-0.6Zr合金组织与性能的影响。结果表明:单独添加Nd或Yb元素后,试验合金的组织明显细化,同时在晶界处形成了γ((Mg,Nd)Zn2)或γ((Mg,Yb)Zn2)三元稀土相;而复合添加Nd和Yb元素后,试验合金的组织不但没有细化,而且在晶界处形成了呈网状分布的γ((Mg,Nd+Yb)Zn2)四元稀土相,并且晶界变宽。经过T4固溶处理后,Mg-5.5Zn-0.6Zr合金中的共晶组织完全溶入基体,而添加Nd、Yb元素后的Mg-5.5Zn-0.6Zr合金晶界处仍有未溶的化合物相存在。其中,添加Yb元素后的Mg-5.5Zn-0.6Zr合金经固溶处理后在晶界处形成了一种新的Mg-Zn-Yb三元球状颗粒相,其常温下的抗拉强度、屈服强度和伸长率分别达到了255.6 MPa、163.6 MPa和17.4%,这主要是因为加入稀土元素Yb后固溶处理产生了复合强化效果。在高温条件下,复合添加稀土元素Nb、Yb后的试验合金具有很好的热稳定性,但其高温塑性比较差。
The effects of rare earth elements Nd and Yb on the microstructure and properties of Mg-5.5Zn-0.6Zr alloy were studied. The results show that the microstructures of the alloy are refined and the γ ((Mg, Nd) Zn2) or γ ((Mg, Yb) Zn2) ternary rare earth phases are formed at the grain boundaries when Nd or Yb is added alone. However, the addition of Nd and Yb elements not only did not refine the microstructure of the alloy, but also formed a grid-like γ ((Mg, Nd + Yb) Zn2) quaternary rare earth phase at the grain boundaries, width. After T4 solution treatment, the eutectic structure of Mg-5.5Zn-0.6Zr alloy completely dissolved in the matrix, while the addition of Nd, Yb element Mg-5.5Zn-0.6Zr alloy grain boundaries still have undissolved compounds Phase exists. Among them, the addition of Yb element Mg-5.5Zn-0.6Zr alloy after solution treatment at the grain boundary to form a new Mg-Zn-Yb ternary spherical particles, its room temperature tensile strength, yield The strength and elongation reached 255.6 MPa, 163.6 MPa and 17.4%, respectively, mainly due to the composite strengthening effect caused by the addition of rare earth element Yb. Under the condition of high temperature, the test alloys with rare earth elements Nb and Yb added have good thermal stability, but their plasticity at high temperature is poor.