(1. 蘭州理工大學(xué) 甘肅省有色金屬新材料省部共建國家重點實驗室，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實驗室，蘭州730050)
摘 要: 利用光學(xué)顯微鏡、X射線衍射儀、掃描電鏡和力學(xué)萬能試驗機研究ZA72鎂合金在不同固溶時間下T6處理后的顯微組織和力學(xué)性能。結(jié)果表明：ZA72鎂合金主要由α-Mg 和分布在晶界的連續(xù)粗大的Mg32(Al, Zn)49和Mg7Zn3相組成，經(jīng)過固溶處理后第二相呈細小的顆粒狀分布在晶界和晶粒上，隨著固溶時間的增加，第二相的尺寸和數(shù)量逐漸減小；經(jīng)T6處理后，細小、彌散的白色點狀強化相在晶界和晶粒內(nèi)部彌散析出，并且隨著固溶時間的增加，析出相的數(shù)量增加；通過T6處理后合金的力學(xué)性能有了明顯的改善，合金的抗拉強度和顯微硬度隨固溶時間的增加呈先上升后下降的趨勢，其中在固溶28 h后抗拉強度出現(xiàn)峰值308 MPa，相對于鑄態(tài)提高了52.4%。
關(guān)鍵字: ZA72鎂合金；固溶時間；顯微組織；力學(xué)性能；T6熱處理
mechanical properties of ZA72 magnesium alloy
（1. State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials,
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:The microstructure and mechanical properties of ZA72 magnesium alloy after T6 heat treatment with different solution times were investigated using optical microscope (OM), X-ray diffractometer (XRD), mechanical apparatus and scanning electron microscope (SEM). The results show that the ZA72 magnesium alloy mainly contains α-Mg, bulky Mg32(Al,Zn)49 and Mg7Zn3 phases which distribute on the grain boundary continuously. After T4 heat treatment, the second phases are converted to fine particles, meanwhile the size and amount have decreased gradually with the solution time increasing. The fine and dispersible white dots precipitates separate out at the grain boundary and grain internal, in addition that the amount of precipitates increase with the solution time extending. The mechanical properties of alloy are obviously improved after T6 heat treatment, the tensile strength and micro-hardness show the trend of arising first and descending later. When the solution time is 28 h, the tensile strength reaches the peak value of 308 MPa, which increases by 52.4% compared with that of the as-cast alloy.
Key words: ZA72 magnesium alloy; solution time; microstructure; mechanical property; T6 treatment
