(沈陽工業(yè)大學 材料科學與工程學院，沈陽 110870)
摘 要: 采用X射線衍射儀(XRD)、掃描電鏡(SEM)和光學顯微鏡(OM)分別研究Mg-5Sn-xSi-0.5Sr(x=1, 2)和Mg-5Sn-ySi-2Sr(y=1, 2)合金的相組成和顯微組織，采用力學性能試驗機測定合金的拉伸性能。結(jié)果表明：Mg-Sn-Si-Sr系合金組織由α-Mg、MgSnSr、Mg2Sn、Mg2Si相所組成。Mg2Si相含量隨Si元素的增加而增加，加入Sr元素會促進MgSnSr相的形成，抑制相界上Mg2Sn相的析出。Sn和Sr均能夠細化Mg2Si相。當Sr含量由0.5%提高到2%(質(zhì)量分數(shù))后Mg2Si和Mg2Sn相均能得到顯著細化，從而顯著提高合金的抗拉強度與屈服強度。
關(guān)鍵字: Mg-Sn-Si-Sr合金；顯微組織；Si影響；Sr影響；力學性能
（School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China）
Abstract:The phase constituent and microstructure of as-cast Mg-5Sn-xSi-0.5Sr (x=1, 2) and Mg-5Sn-ySi-2Sr (y=1, 2) alloys were analyzed by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and optical microscopy (OM), respectively. The mechanical tester was employed to obtain the tensile properties of the alloys. The results show that MgSnSr, Mg2Sn and Mg2Si phases are precipitated on the α-Mg phase boundary or in the phase for as-cast Mg-Sn-Si-Sr series alloys. The volume fractions of Mg2Si phase increase with the Si element increasing. The addition of Sr element can promote the formation of MgSnSr phase and inhibit the precipitation of Mg2Sn phase on the phase boundary. While the Mg2Si phase can be refined through adding Sn and Sr elements. Furthermore, when the Sr content increases from 0.5% to 2% (mass fraction), both the Mg2Si and Mg2Sn phases are refined significantly. Therefore, the tensile and yield strengths of the alloys are obviously enhanced.
Key words: Mg-Sn-Si-Sr alloys; microstructure; Si effect; Sr effect; mechanical properties
