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.
展开▼
机译:Microstructural evolution and mechanical properties of FeCoCrNiCu high entropy alloys:a microstructure-based constitutive model and a molecular dynamics simulation study
机译:Etude du Comportement micro-mecanique d'Une Vitroceramique a subst de siO2-al2O3-Li2O en Liaison avec la microstructure(siO2-al2O3-Li2O玻璃陶瓷的微观力学行为及其与微结构的关系研究)