Al-Sc-Zr合金におけるAl₃(Sc,Zr) 複合析出粒子のSTEM-EDS解析

抄録

The ternary Al₃Sc_1-XZr_X precipitates formed in the Al-0.15mass%Sc-0.16mass%Zr alloy aged at 763 K for up to 10⁶s were analyzed with the STEM-EDS technique, and the nucleation and growth process for the precipitates were discussed. The obtained results show that the precipitates with 23-53 nm in radius were revealed to consist of Al₃Sc_1-XZr_X phase with increasing substitution ratio, X, from the center toward the surface. The binary Al₃Sc phase precipitates preferentially in the early stage of aging (10³s-10⁴s), and the Al₃Sc_1-XZr_X phases cover the Al₃Sc nucleus in the later stage of aging (10⁵s-10⁶s). The composite particle in the ternary Al-0.15Sc-0.16Zr alloy has a smaller growth rate than the binary Al₃Sc particle in the binary Al-0.20Sc alloy at 763 K. These results were well understood in terms of slower diffusion of Zr than Sc in the matrix.