| Title |
A Study on the Precipitation Behavior in Rapidly Solidified Al - Li - Zr Ternary Alloys |
| Authors |
정해용(Hae Young Jeong); 윤재성(Jae Seong Yoon); 박세윤(Se Yun Park); 김인배(In Bae Kim) |
| Abstract |
The precipitation behavior of rapidly solidified Al-Li-Zr alloys has been investigated after melt quenching and after subsequent aging at temperatures ranging from 160 to 240℃, by using a transmission electron microscopy and microhardness measurements. Metastable δ` and β` phases which are nearly spherical in shape are present in the as quenched condition. Composite precipitates are controlled by diffusion of Li atoms onto the initial morphology of β` phase. Heterogeneous precipitations are interpreted in terms of a combination of excess vacancies and capillarity effects on the particle stability at elevated temperatures. Precipitate free zone(PFZ) occurred by heterogeneous precipitation of δ phase formed perferentially at grain boundaries. The width of PFZ increased with (aging time)^½. From the analysis of the growth kinetics of PFZ, diffusivity was obtained to be 1.028×10^(-15)㎝/s at 240℃. |