単ロール法によって急冷凝固されたAl-8 mass%Fe合金リボンの組織と機械的性質

抄録

Microstructure and mechanical properties of melt spun Al-8 mass%Fe alloy ribbons have been investigated. The solidification structure is composed of two zones. Zone A found on the substrate side of ribbon has a limited etching response and the Vickers hardness of 2.1 GPa while zone B found on the air side and darkened by etching has the Vickers hardness of 1.1-1.3 GPa. The increase in roller surface velocity from 17 to 27 m/s results in the decrease in ribbon thickness from 63 to 42 μm associated with the increase in area fraction of zone A from 0.2 to 0.7. The ribbon hardness consequently increases with decrease in ribbon thickness, though the hardness of zone A and B is independent of ribbon thickness. As for the ribbons whose area fractions of zone A are not less than 0.34, the 0.2% proof stress σ_y0.2 and ultimate tensile strength σ_TS at room temperature are related to the ribbon hardness H_vr as; σ_y0.2=0.31 H_vr and σ_TS=0.34 H_vr respectively.
In order to calculate the area fraction of zone A, a solidification model considering the kinetics of α-Al dendrite growth in the undercooled alloy melt is also presented.