【摘要】 研究了Mg-6Gd-4Y（质量分数,%）合金与添加质量分数1%Zn的Mg-6Gd-4Y-1Zn合金的显微组织与力学性能。结果表明:Mg-6Gd-4Y合金的铸态组织由?-Mg基体和Mg₂₄（GdY）₅两相组成。而含有Zn的Mg-6Gd-4Y-1Zn合金的铸态组织则主要由α-Mg,Mg₂₄（GdY）₅和具有18R-LPSO结构的Mg₁₂Y₁Zn₁相组成。挤压后,在含锌合金中发现了14H-LPSO相,分布于条状分布的Mg₁₂Y₁Zn₁之间。14H-LPSO相的形成机理为沉淀析出,反应可表示为α-Mg′→α-Mg+14H。Zn含量对β系列沉淀物没有明显的影响。在Mg-6Gd-4Y合金和Mg-6Gd-4Y-1Zn合金上进行的时效（T6和T5）处理均引起β’析出相的形成。T6处理后的Mg-6Gd-4Y-1Zn合金具有高抗拉伸强度和良好的延展性,屈服强度（YS）,抗拉强度（UTS）和延伸率分别为309 MPa,438 MPa和6.8%。这是18R-LPSO相与细小弥散分布的14H-LPSO相和β’沉淀相共同作用的结果。更多还原

【Abstract】 Microstructures and mechanical properties of the Mg-6Gd-4Y（wt%）alloys with and without 1wt%Zn additions were investigated.The results show that the as-cast microstructure of the Mg-6Gd-4Y alloy consist of?-Mg matrix and Mg₂₄（GdY）₅secondary phase.However,the as-cast microstructure of the Zn-containing Mg-6Gd-4Y-1Zn alloy consist of?-Mg matrix,Mg₂₄（GdY）₅ secondary phase and Mg₁₂Y₁Zn₁ phase which has a 18R long period staking ordered（18R-LPSO）structure.After extrusion a 14H-LPSO phase is found in the Zn-containing alloy which is distributed between the 18R-LPSO strips in the as extruded microstructure.The formation mechanism of the 14H-LPSO phase is precipitation,and the reaction can be expressed as‘α-Mg′→α-Mg+14H’.Zn content has no obvious effect on the precipitation ofβseries.Aged（T6 and T5 treatment）conducted on both the Mg-6Gd-4Y alloy and the Mg-6Gd-4Y-1Zn alloy causes the formation ofβ’precipitates.The T6-aged Mg-6Gd-4Y-1Zn alloy exhibits high tensile strength combined with good ductility,and the values of the yield strength（YS）,ultimate tensile strength（UTS）and elongation are 309 MPa,438 MPa and 6.8%,respectively.It is due to the coexistence of 18R-LPSO phase and finely dispersed distribution of the 14H-LPSO phase and theβ’precipitates in the microstructure.更多还原