(1. 蘭州理工大學(xué) 省部共建有色金屬先進(jìn)加工與再利用國(guó)家重點(diǎn)實(shí)驗(yàn)室，蘭州 730050； 2. 蘭州理工大學(xué) 有色金屬合金及加工教育部重點(diǎn)實(shí)驗(yàn)室，蘭州 730050)
摘 要: 通過(guò)在Mg-6Zn合金中添加0.4%Zr和2%Sm(質(zhì)量分?jǐn)?shù))制備出一種新型Mg-6Zn-2Sm-0.4Zr合金；利用光學(xué)顯微鏡(OM)、掃描電鏡(SEM)及能譜儀(EDS)、X射線衍射儀(XRD)、顯微硬度及力學(xué)性能測(cè)試研究鑄造Mg-6Zn-2Sm-0.4Zr合金在鑄態(tài)、固溶、時(shí)效處理下的顯微組織和力學(xué)性能的變化。結(jié)果表明：合金鑄態(tài)組織主要由基體α-Mg、晶界處呈連續(xù)或半連續(xù)分布的(α-Mg+Mg2Zn3+Mg41Sm5)共晶和晶內(nèi)孤立的點(diǎn)狀相組成。合金在440和450 ℃固溶12~36 h時(shí)間范圍內(nèi)，隨著時(shí)間和溫度的增加，固溶效果逐漸增強(qiáng)。當(dāng)在450℃固溶28 h時(shí)獲得了較好的顯微組織，抗拉強(qiáng)度為230 MPa，伸長(zhǎng)率為9.58%。隨后經(jīng)200 ℃時(shí)效6~48 h后，合金的力學(xué)性能明顯提高，時(shí)效強(qiáng)化效應(yīng)隨時(shí)間的延長(zhǎng)呈先增加后減小的趨勢(shì)，其中時(shí)效12 h時(shí)同時(shí)出現(xiàn)了抗拉強(qiáng)度和伸長(zhǎng)率的峰值258 MPa和14.43%，比鑄態(tài)的分別提高44 MPa和90.80%。
關(guān)鍵字: Mg-6Zn-2Sm-0.4Zr鎂合金；固溶處理；時(shí)效處理；顯微組織；力學(xué)性能
（1. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China; 2. Key Laboratory of Non-ferrous Metal Alloys and Processing, Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:A new type Mg-6Zn-2Sm-0.4Zr alloy was fabricated by adding 0.4%Zr and 2%Sm (mass fraction) in Mg-6Zn alloy, and the microstructure and mechanical properties of the cast alloy under the conditions of as-cast, solution and aging treatment were investigated by optical microscopy (OM), scanning electron microscopy (SEM) with equipped energy dispersive spectrometry (EDS), X-ray diffractometry (XRD), micro-hardness and mechanical tests. The results indicate that the as-cast alloy is mainly composed of matrix α-Mg, eutectic phases (α-Mg+Mg2Zn3+Mg41Sm5) with continuous or semi-continuous morphology distributed along grain boundaries and a few isolated particles inside grains. The alloy is solutionized at 440 ℃ and 450 ℃ for 12-36 h, with the increment of solution temperature and time, the solution effect gradually increases. When the alloy is treated at 450 ℃ for 28 h, the alloy exhibits relatively homogeneous microstructure and attains mechanical performance with ultimate tensile strength (UTS) of 230 MPa and elongation (EL) of 9.58%, respectively. After the alloy being aged at 200 ℃ for 6-48 h, the mechanical properties of alloy increase obviously, and the aging strengthening effect increases firstly and then decreases, the peak values of UTS (258 MPa) and EL (14.43%) of the alloy aged at 200 ℃ for 12 h are simultaneously obtained, which are increased by 44 MPa and 90.80% compared with those of the as-cast alloy, respectively.
Key words: Mg-6Zn-2Sm-0.4Zr magnesium alloy; solution treatment; aging treatment; microstructure; mechanical property
