(大連理工大學(xué) 材料科學(xué)與工程學(xué)院，大連 116024)
摘 要: 通過(guò)金屬模鑄、熱擠壓和時(shí)效處理(T5)工藝過(guò)程制備出高強(qiáng)Mg-7Gd-4Y-1.6Zn-0.5Zr合金，并利用光學(xué)顯微鏡、XRD、SEM及TEM分析研究Mg合金不同狀態(tài)下的顯微組織和力學(xué)性能。結(jié)果表明：Mg-7Gd-4Y-1.6Zn-0.5Zr合金的鑄態(tài)組織主要由α-Mg基體和沿晶界分布的片層狀第二相Mg12Zn(Gd, Y)組成，經(jīng)過(guò)熱擠壓變形后，合金晶粒顯著細(xì)化，時(shí)效處理過(guò)程中Mg12Zn(Gd, Y)相上析出少量細(xì)小的顆粒狀Mg3Zn3(Gd, Y)2相。時(shí)效態(tài)合金的抗拉強(qiáng)度、屈服強(qiáng)度和伸長(zhǎng)率分別達(dá)到446 MPa、399 MPa和6.1%，其強(qiáng)化方式主要為細(xì)晶強(qiáng)化和第二相強(qiáng)化。
關(guān)鍵字: 高強(qiáng)鎂合金；稀土；熱擠壓；時(shí)效處理；力學(xué)性能
high-strength Mg-Gd-Y-Zn-Zr alloy
（School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China）
Abstract:High-strength Mg-7Gd-4Y-1.6Zn-0.5Zr alloy was prepared by conventional metal mold casting，subsequently hot extrusion and T5 heat treatment were conducted. The microstructures and mechanical properties of this Mg alloy under different states were studied by using OP, XRD, SEM and TEM. The results show that the as-cast microstructures of Mg-7Gd-4Y-1.6Zn-0.5Zr alloy consists of α-Mg matrix and lamellar second-phase Mg12Zn(Gd, Y) phase which distributes around α-Mg matrix. After hot extrusion, the grain size of this alloy can be refined dramatically. Tiny little particle Mg3Zn3(Gd, Y)2 phase is precipitated out of the Mg12Zn(Gd, Y) phase during the process of T5 heat treatment. The tensile strength, yield strength and elongation of alloys under T5 condition reach 446 MPa, 399 MPa and 6.1%, respectively. The main strengthening methods are considered as fine grain strengthening and second-phase strengthening.
Key words: high-strength magnesium alloy; rare earth; hot extrusion; T5 heat treatment; mechanical property
