(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083； 2. 中南大學(xué) 輕合金研究院，長沙 410083； 3. 中南大學(xué) 有色金屬先進(jìn)結(jié)構(gòu)材料與制造協(xié)同創(chuàng)新中心，長沙 410083)
摘 要: 通過金相觀察、X射線衍射、透射電鏡、硬度測試和拉伸性能測試等實驗方法，研究添加不同含量的Nd元素對Mg-6Gd-2.5Y-0.5Zr合金的顯微組織、時效硬化行為以及峰值時效下力學(xué)性能的影響。結(jié)果表明：隨著Nd含量的增加，鑄態(tài)合金中第二相Mg5(Gd/Y)和Mg24(Gd/Y)5 的含量顯著增加，合金經(jīng)固溶淬火后，時效強(qiáng)化現(xiàn)象越來越顯著，峰值時效時間縮短，峰值時效硬度明顯增加。當(dāng)Nd元素的含量為1.0%(質(zhì)量分?jǐn)?shù))，合金的力學(xué)性能最佳，Mg-6Gd-2.5Y-1Nd-0.5Zr的抗拉強(qiáng)度為289 MPa，屈服強(qiáng)度為241 MPa。時效硬化行為和峰值時效力學(xué)性能得到改善，其主要是因為加入Nd元素后，在α-Mg基體中形成大量的β′相，且β′相明顯細(xì)化，β′相的形貌也發(fā)生改變。
關(guān)鍵字: Nd元素；鎂合金；顯微組織；力學(xué)性能
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China; 2. Light Alloy Research Institute, Central South University, Changsha 410083, China; 3. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Central South University, Changsha 410083, China）
Abstract:The effects of Nd addition on microstructure, age-hardening behavior and mechanical properties of Mg-6Gd-2.5Y-0.5Zr alloy were investigated by optical microscopy (OM), X-ray diffractometry (XRD), transmission electron microscopy (TEM), hardness test and tensile tests. The results show that the amount of second phase (Mg5(Gd/Y) and Mg24(Gd/Y)5) increase significantly in the as-cast alloys, and the age hardening response after quenched is improved apparently with the addition of Nd, the hardness is enhanced and time to peak ageing is shortened. The Mg-6Gd-2.5Y-1Nd-0.5Zr alloy exhibits the maximum yield strength of 241 MPa and ultimate tensile strength of 289 MPa. The reason for the improvement of age-hardening behavior and mechanical properties is the higher number density and finer β′ precipitates in the α-Mg matrix, and morphologies of β′ precipitates also change with Nd addition.
Key words: neodymium; magnesium alloy; microstructure; mechanical property
