摘要
Although icosahedral quasicrystal phase(denoted as I-phase)has been verified as an outstanding reinforcing phase,the mechanical properties of quasicrystal-reinforced Mg-Zn-Y alloys fabricated by traditional casting processes are still unsatisfactory due to the serious segregation of intermetallic compounds.In this study,the microstructure and mechanical properties of Mg-12Zn-2Y alloy fabricated by different casting processes,including permanent mold casting,squeeze casting and rheo-squeeze casting with ultrasonic vibration,were systematically investigated and compared.The results show that massive,large-sized I-phase and Mg7Zn3 phase gather together in the permanent mold cast sample,while the squeeze casting process leads to the transformation of I-phase into fine lamellar morphology and the amount of Mg7Zn3 decreases.As to the rheo-squeeze casting process,when the ultrasonic vibration is exerted with power from 800 W to 1,600 W,theα-Mg grains are refined and spheroidized to a large extent,and the lamellar spacing of the eutectic structure is significantly reduced,accompanied by some tiny granular I-phase scattering in theα-Mg matrix.However,when the ultrasonic power continuously increases to 2,400 W,the eutectic structure becomes coarse.The best mechanical properties of the rheo-squeeze cast alloy are obtained when the ultrasonic power is 1,600 W.The microhardness,yield strength,ultimate tensile strength and elongation are 79.9 HV,140 MPa,236 MPa,and 3.25%,which are 44.1%,26.1%,25.5%,132.1%respectively higher than the corresponding values of the squeeze casting sample,and are 47.6%,44.3%,69.8%,and 253.3%respectively higher than the corresponding values of the permanent mold casting sample.
基金
financially supported by the Natural Science Foundation of Anhui Province(No.1908085QE197)
the State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2019-024)
the Fundamental Research Funds for the Central Universities(JZ2019HGTA0043)。
作者简介
Xiao-gang Fang,Male,born in 1989,Ph.D.His research interests mainly focus on the development of new light alloy materials,liquid metal forming technology,and numerical simulation of the casting process.To date,he has published more than 20 technical papers.E-mail:fangxg@hfut.edu.cn。
