粗大化した結晶粒より成る Al-4 wt% Cu 合金の機械的性質に及ぼす溶質偏析の影響

概要

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Al-4wt% Cu alloy ingots with solute segregation were produced by iterative casting with seed, and their structures and mechanical properties were measured. The grain size increased with the iterative casting, and the ingot after the 4th iterative casting consisted of almost one grain. The primary arm spacing λ_p and the secondary arm spacing λ_s had relations with the cooling rate V and the local solidification time θ;λ_p [mm]=0.17・υ^<-0.56> [K/s], and λ_s [mm]=0.015・θ^<0.29> [s]. These agreed well with the previous results for alloys consisting of columnar grains or equiaxed grains. The yield strength σ_y, the ultimate tensile strength UTS and the elongation of 4th ingot decreased with primary arm spacing λ_p. After heat treatment, there was no dependence of σ_y and UTS_L (parallel to primary arms) on the spacing λ_p, but UTS_T (perpendicular to primary arms and parallel to secondary arms) and the elongation varied with λ_p. These results imply that σ_y and UTS_L are largely affected by the solute segregation, and UTS_T and the elongation are largely affected by cavities and micro-cracks created during solidification.
社団法人日本材料学会の論文
1989-04-15