(武漢理工大學(xué) 材料科學(xué)與工程學(xué)院，武漢 430070)
摘 要: 采用SEM、EDS和XRD等測試手段研究粉末原位合成法制備的Mg-50%Al4C3中間合金對AZ91D鎂合金顯微組織的細化效果。結(jié)果表明：中間合金的加入可顯著細化AZ91D鎂合金的α-Mg晶粒。當(dāng)Al4C3的含量為1.0%時，α-Mg晶粒的尺寸由基體合金的142.9 μm降至63.2 μm，降低幅度約為56%，且共晶組織形貌發(fā)生明顯改變，由完全離異的骨骼狀β共晶組織和共生生長層片狀α+β共晶組織轉(zhuǎn)變?yōu)榉涓C狀的α+β部分離異共晶組織，同時β相的尺寸變小、分布更趨彌散。通過能譜分析、面錯配度計算及差熱分析，證實Al4C3可成為初生α-Mg晶粒的良好異質(zhì)核心。此外，顯微組織的細化導(dǎo)致合金力學(xué)性能的提高。
關(guān)鍵字: AZ91D鎂合金；Mg-Al4C3中間合金；晶粒細化；力學(xué)性能
AZ91D Mg alloy
（School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China）
Abstract:The refinement effect of Mg-50%Al4C3 (mass fraction) master alloy on microstructures of AZ91D magnesium alloy was studied using SEM, EDS and XRD, and so on. The results show that the grain size of α-Mg in AZ91D alloy is apparently reduced after adding Mg-Al4C3 master alloy. When the content of Al4C3 is 1.0%, the average grain size of the α-Mg grain decreases from about 142.9 μm of AZ91D base alloy to 63.5 μm, the reduced extent is about 56%. Meanwhile, the eutectic morphologies obviously change from the fully-divorced β eutectic and lamellar α+β eutectic structure into honeycomb α+β partially-divorced eutectic structure, and the size of β phase diminishes and tends to dispersed distribution. Based on the analysis of EDS, DTA and calculation of the planar disregistry between Al4C3 and Mg, Al4C3 particles can act as the heterogeneous nucleus of primary α-Mg phase. In addition, the addition of Al4C3 improves the mechanical properties of AZ91D alloy obviously.
Key words: AZ91D Mg alloy; Mg-Al4C3 master alloy; grain refinement; mechanical properties
