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采用DSC热分析仪、金相显微镜、扫描电镜和显微硬度计等研究了AZ80-2.0Ca铸造镁合金的微观组织,分析了均匀化热处理后合金的微观组织演变和显微硬度的变化规律。结果表明,该合金由基体α-Mg相,β-Mg17Al12相和(Mg,Al)2Ca相组成;Ca元素的加入使β-Mg17Al12相的熔点由437℃提高到457℃;在430℃下保温2h时β-Mg17Al12相完全溶解,继续延长保温时间至24h时,(Mg,Al)2Ca相未见溶解;当合金在515℃保温0.5h时,β-Mg17Al12相完全溶解,继续延长保温时间至4h时,(Mg,Al)2Ca相开始分解并转变为Al2Ca和Mg;合金共晶相分解后,其硬度开始下降,分解完成后其硬度趋于稳定,且515℃均匀化热处理后的合金硬度小于430℃均匀化热处理后的合金硬度。
The microstructure of AZ80-2.0Ca cast magnesium alloy was studied by DSC thermal analyzer, metallographic microscope, scanning electron microscope and microhardness tester. The microstructure evolution and microhardness of AZ80-2.0Ca alloy were analyzed. The results show that the alloy consists of α-Mg phase, β-Mg17Al12 phase and (Mg, Al) 2Ca phase. When Ca is added, the melting point of β-Mg17Al12 phase increases from 437 ℃ to 457 ℃. (Mg, Al) 2Ca phase did not dissolve when the holding time was prolonged for 24 hours. When the alloy was incubated at 515 ℃ for 0.5h, the phase of β-Mg17Al12 was completely dissolved and the holding time was prolonged to 4h, the (Mg, Al) 2Ca phase began to decompose and transformed into Al2Ca and Mg. After the eutectic phase decomposition, the hardness began to decrease and the hardness became stable after the decomposition, and the alloy hardness Less than 430 ℃ uniform heat treatment after the alloy hardness.