Microstructure and microhardness of nanostructured Al-4.6Cu-Mn alloy ribbons
来源期刊：International Journal of Minerals Metallurgy and Materials2015年第8期
论文作者：Zhong-wei Chen Qin-ying Fan Kai Zhao
文章页码：860 - 867
摘 要：The microstructural characteristics and microhardness of nanostructured Al-4.6Cu-Mn ribbons produced by melt spinning were investigated using field-emission gun scanning electron microscopy, transmission electron microscopy, and hardness testing, and the results were compared to those of similar ribbons manufactured by direct-chill casting. It is shown that the nanostructure of the as-melt-spun ribbons consists of α-Al dendrites with a secondary dendrite arm spacing of approximately 0.55-0.80 μm and ultrafine eutectic crystals of a nanosized scale of approximately 100-200 nm on dendritic boundaries. The solidification time and cooling rate of 46-μm-thick ribbons were estimated to be 1.3 × 10-6 s and 4.04 × 106 K·s-1, respectively. At an aging temperature of 190°C, the coherent θ″ phase in aged ribbons gradually transforms into nanoscale θ′-phase platelets as the aging time is extended from 2 to 8 h; the rod-like morphology of the T（Al20Cu2Mn3） dispersoid with 120-160-nm diameter also forms, which results in peak aging hardness. The precipitation behaviors of aged ribbons cannot be changed at the high cooling rates of as-cast ribbons. However, a finer and more uniformly distributed microstructure and a supersaturated solid solution at a high cooling rate can shorten the time required to obtain a certain aging hardness before peak hardness.
Zhong-wei Chen，Qin-ying Fan，Kai Zhao
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University
摘 要：The microstructural characteristics and microhardness of nanostructured Al-4.6Cu-Mn ribbons produced by melt spinning were investigated using field-emission gun scanning electron microscopy, transmission electron microscopy, and hardness testing, and the results were compared to those of similar ribbons manufactured by direct-chill casting. It is shown that the nanostructure of the as-melt-spun ribbons consists of α-Al dendrites with a secondary dendrite arm spacing of approximately 0.55-0.80 μm and ultrafine eutectic crystals of a nanosized scale of approximately 100-200 nm on dendritic boundaries. The solidification time and cooling rate of 46-μm-thick ribbons were estimated to be 1.3 × 10-6 s and 4.04 × 106 K·s-1, respectively. At an aging temperature of 190°C, the coherent θ″ phase in aged ribbons gradually transforms into nanoscale θ′-phase platelets as the aging time is extended from 2 to 8 h; the rod-like morphology of the T（Al20Cu2Mn3） dispersoid with 120-160-nm diameter also forms, which results in peak aging hardness. The precipitation behaviors of aged ribbons cannot be changed at the high cooling rates of as-cast ribbons. However, a finer and more uniformly distributed microstructure and a supersaturated solid solution at a high cooling rate can shorten the time required to obtain a certain aging hardness before peak hardness.
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