(沈陽(yáng)航空航天大學(xué) 材料科學(xué)與工程學(xué)院，沈陽(yáng) 110136)
摘 要: 為提高高硅Mg-Si-Zn合金的性能，實(shí)驗(yàn)通過(guò)調(diào)整Ca、Y變質(zhì)劑的含量，研究在Ca變質(zhì)、Ca-Y復(fù)合變質(zhì)作用下高硅Mg-Si-Zn合金的凝固組織與性能。結(jié)果表明：在Mg-4Si-4Zn合金中加入Ca，可使合金凝固組織中初生Mg2Si相由粗大的枝晶形貌轉(zhuǎn)變?yōu)榧?xì)小的矩形塊狀形貌，共晶組織由粗大的漢字狀轉(zhuǎn)變?yōu)辄c(diǎn)棒狀；當(dāng)Ca加入量為0.7%時(shí)(質(zhì)量分?jǐn)?shù))變質(zhì)效果最為明顯；當(dāng)Ca加入量超過(guò)0.7%后，合金中會(huì)形成CaMgSi棒狀相，這是Ca變質(zhì)效果下降的一個(gè)主要原因。當(dāng)合金中Ca加入量為0.7%時(shí)，再加入Y會(huì)將初生Mg2Si相由規(guī)則平整形貌轉(zhuǎn)變?yōu)閹в袦羡挚锥吹膹?fù)雜形貌，而相的尺寸基本不發(fā)生改變，這使得經(jīng)Ca-Y復(fù)合變質(zhì)的Mg-4Si-4Zn合金的硬度顯著高于Ca單一變質(zhì)合金的，硬度提高超過(guò)10%。
關(guān)鍵字: Mg-Si-Zn合金；復(fù)合變質(zhì)；Mg2Si；凝固組織
（School of Materials Science and Engineering, Shenyang Aerospace University, Shenyang 110136, China）
Abstract:By changing the addition of Ca and Y, the solidified microstructure and properties of Mg-Si-Zn alloy with high Si content were investigated under the condition of Ca modification and Ca-Y compound modification. The results show that, the Ca addition in to Mg-4Si-4Zn alloy has obvious modification effect, with the primary phase morphology of Mg2Si transforming from big dendrite to small regular square block and the morphology of eutectic Mg2Si changing from complex Chinese pattern to point bar. The most obvious effect of modification is near the Ca addition of 0.7% (mass fraction), and CaMgSi bar phase will precipitate from the alloy melt while Ca addition is more than 0.7%, reducing the Ca modification. When the Ca addition is 0.7%, the primary Mg2Si transforms from regular square to complex morphology with ravine holes without the obvious change of phase size by the Y addition. The alloy hardness after Ca-Y compound modification is obviously higher than that after Ca modification, with the hardness increasing by more than 10%.
Key words: Mg-Si-Zn alloy; compound modification; Mg2Si; solidified microstructure
