(1. 蘭州理工大學 省部共建有色金屬先進加工與再利用國家重點實驗室，蘭州 730050； 2. 蘭州理工大學 有色金屬合金及加工教育部重點實驗室，蘭州 730050)
摘 要: 通過金屬型鑄造制備新型Mg-6Zn-3Al(ZA63，質(zhì)量分數(shù)，%)鎂合金，并利用光鏡(OM)、掃描電鏡(SEM)、透射電鏡(TEM)、X射線衍射儀(XRD)和力學性能測試研究ZA63合金在鑄態(tài)、固溶和時效處理后顯微組織和力學性能的變化規(guī)律。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+Mg7Zn3+Mg32(Al,Zn)49)共晶和晶內(nèi)孤立的顆粒相組成。合金在350 ℃固溶12~36 h時，隨著時間延長，固溶效果逐漸增強，且在28 h時獲得了較好的組織和241 MPa的抗拉強度及11.12%的伸長率。隨后在180 ℃時效 6~72 h后，合金的抗拉強度進一步提高，力學性能隨保溫時間延長呈先增加后減小的趨勢，其中時效24 h時同時出現(xiàn)抗拉強度、伸長率和硬度的峰值298 MPa、9.78%和96.3 HV，比鑄態(tài)的214 MPa、8.54%、62.2 HV分別提高39.25%、14.52%和54.82%。180 ℃時效24 h后，析出相的主要形態(tài)有板條狀和短棒狀。
關(guān)鍵字: Mg-6Zn-3Al鎂合金；固溶處理；時效處理；顯微組織；力學性能；析出相形態(tài)
（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-3Al (noted ZA63, mass fraction, %) magnesium alloy was prepared by permanent mould casting, and the microstructure and mechanical properties of the alloy under the conditions of as-cast, solution and aging treatment were systematically investigated by OM, SEM, TEM, XRD and mechanical tests, respectively. The results indicate that the as-cast alloy is mainly comprised of matrix α-Mg, eutectic phases (α-Mg+Mg2Zn3+Mg7Zn3+ Mg32(Al,Zn)49) with continuous or semi-continuous precipitated along grain boundaries and a few divorced granules within grains. When the alloy is treated at 350 ℃ for 12-36 h, the solution effects are gradually enhanced with increasing solution time. At 350 ℃ for 28 h, the alloy reveals relatively homogeneous microstructure, and the ultimate tensile strength (UTS) and elongation (EL) of 241 MPa and 11.12% are achieved, respectively. Subsequently, when the alloy is aged at 180 ℃ for 6-72 h, the mechanical test demonstrates that, the UTS further increases, the mechanical properties increase firstly and then decrease, the peak values of UTS, EL and micro-hardness of the alloy aged at 180 ℃ for 24 h are simultaneously obtained, which are 298 MPa, 9.78% and 96.3 HV and increase by 39.25%, 14.52% and 54.82% compared with those of the as-cast alloy (214 MPa, 8.54% and 62.2 HV), respectively. There are mainly two types of precipitates of the alloy after aging at 180 ℃ for 24 h, namely, the first precipitate is lath-like, the secondary one is a short-rod.
Key words: Mg-6Zn-3Al magnesium alloy; solution treatment; aging treatment; microstructure; mechanical property; precipitation morphology
