Microstructural development and mechanical properties of drop tube atomized Al-2.85 wt% Fe
Microstructural development and mechanical properties of drop tube atomized Al-2.85 wt% Fe
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DOI：
10.1016/j.jmst.2021.05.085
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发表时间：
2022-03
影响因子：
10.9
通讯作者：
M. Abul;R. Cochrane;A. Mullis
中科院分区：
文献类型：
--
作者：
M. Abul;R. Cochrane;A. Mullis
摘要采用6.5m落管对Al-2.85wt%Fe合金进行了非平衡无容器凝固。收集球形样品并将其筛分成从850 μm到53 μm的7个粒度级，估算的冷却速率分别为150到11000 K s-1。XRD分析结果表明，所有尺寸的熔滴都形成了Al、Al 6 Fe和Al 13 Fe 4相，而Al 5 Fe 2相只出现在直径≤ 150 μm的熔滴中。通过使用SEM和光学显微镜进行显微组织评价，表明直径大于300 µm的液滴表现出不同的形态;微孔、枝晶α-Al与枝晶间Al 13 Fe 4共晶和Al-Al 6 Fe共晶区域。随着冷却速度的增加，Al-Al 6 Fe区消失。EDX分析表明，随着冷却速度的增加，α-Al中的固溶Fe含量从0.37wt%Fe增加到1.105wt%Fe，共晶分数从49.7vol. %至26.7体积%。片层间距的测量允许的共晶生长速度和界面过冷度的计算，其中的共晶耦合区的富铝边界可以重建。这表明耦合区明显偏向共晶的金属间侧。为了了解非平衡凝固对液滴力学性能的影响，测量了液滴的显微硬度。对于直径≥ 850 μ m和直径≤ 75 μ m的液滴，显微硬度分别从55.3HV0.01提高到66.5HV0.01。
Abstract Al-2.85 wt% Fe alloy has been subjected to non-equilibrium container-less solidification using a 6.5 m drop tube. Spherical samples were collected and sieved into 7 sizes fractions ranging from 850 μm to 53 μm, with the estimated cooling rates being 150 to 11000 K s-1 respectively. XRD analysis was employed on all droplet size fractions for identification and evolution of the phases, showing that Al, Al 6 Fe and Al 13 Fe 4 were formed for all sizes while Al 5 Fe 2 was observed only in droplets≤ 150 μm in diameter. Microstructural evaluation was conducted by using SEM and optical microscopy, showing that droplet larger than 300 µm in diameter exhibited distinct morphologies; microcellular, dendritic α-Al with inter-dendritic Al 13 Fe 4 eutectic and an Al-Al 6 Fe eutectic region. With increasing cooling rate, the Al-Al 6 Fe region disappears. EDX analysis reveals that increasing the cooling rate increased the dissolved Fe content in α-Al from 0.37 wt% Fe to 1.105 wt% Fe, and correspondingly the eutectic fraction decreased from 49.7 vol.% to 26.7 vol.%. Measurement of the lamellar spacing allowed the eutectic growth velocity and interfacial undercooling to be calculated, wherein the Al-rich boundary of the eutectic coupled zone could be reconstructed. This shows a coupled zone skewed significantly towards the intermetallic side of the eutectic. In order to understand the effect of non-equilibrium the solidification on the mechanical properties micro hardness of the droplets was measured. The micro-hardness has risen from 55.3 HV 0.01 to 66.5 HV 0.01 for≥ 850 μ m and≤ 75 μ m droplets, respectively.