(1. 東北大學(xué) 材料與冶金學(xué)院， 沈陽 110004；
2. 華中科技大學(xué) 塑性成型模擬及模具技術(shù)國家重點(diǎn)實(shí)驗(yàn)室， 武漢 430074)
摘 要: 研究機(jī)械振動(dòng)對(duì)消失模鑄造AZ91合金微觀組織和力學(xué)性能的影響， 并分析凝固過程中機(jī)械振動(dòng)細(xì)化晶粒的機(jī)制。 結(jié)果表明： 機(jī)械振動(dòng)能顯著地細(xì)化消失模鑄造AZ91合金的組織， 合金組織由α-Mg固溶體、 沉淀Mg17Al12和新相Al13Mn12組成， 其鋁錳相有別于不施加振動(dòng)時(shí)的Al32Mn25相； 機(jī)械振動(dòng)較大幅度改善了合金的力學(xué)性能， 當(dāng)激振力為1.5 kN時(shí)， AZ91合金抗拉強(qiáng)度相對(duì)于不振動(dòng)時(shí)提高27％， 其合金力學(xué)性能最優(yōu)； 而當(dāng)激振力進(jìn)一步增加時(shí)， 由于組織中存在著微觀縮松， 強(qiáng)度有所降低。 機(jī)械振動(dòng)法通過增大過冷度、 剪切力碎化枝晶和使枝晶臂熔斷來細(xì)化晶粒。
關(guān)鍵字: AZ91鎂合金； 消失模鑄造； 機(jī)械振動(dòng)； 力學(xué)性能
（1. School of Materials and Metallurgy, Northeastern University,
Shenyang 110004, China;
2. State Key Laboratory of Plastic Forming and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China）
Abstract: The effects of mechanical vibration on the microstructure and mechanical properties of AZ91 magnesium alloy were investigated via lost foam casting (LFC). The refining microstructure mechanism of the casting alloy under vibration force was also analyzed. The results show that mechanical vibration can produce finer dendrite in AZ91 alloy. The microstructure of AZ91 alloy via LFC consists of dominant α-Mg and β-Mg17Al12 as well as a new phase Al13Mn12 which is different from Al32Mn25 in the untreated AZ91 alloy via LFC. The mechanical vibration can also strongly improve the mechanical properties of AZ91 alloy. The value of tensile strength of AZ91 alloy produced under vibration force of 1.5 kN is increased by 27% compared to that under vibration force of 0 kN and the mechanical properties is ultimate. However, the strength of AZ91 alloy drops due to the presence of the microporosity in the casting when the vibration force is increased. Mechanical vibration produces finer dendrite by increasing the undercooling degree, breaking dendrite into pieces by shear stress and melting the secondary dendrite arm.
Key words: AZ91 magnesium alloy; lost foam casting; mechanical vibration; mechanical property
