| Ternary Al-Ti-X(X=B, V, Ce, Zr) alloy powders were produced by mechanical alloying and compacted in Cu can, then extruded into a rod at 550℃, STEM micrographs and EDS analyses of the as-extruded bar revealed the 3rd element such as V, Zr, Ce only in the precipitates of Al₃Ti substituting the Ti. The precipitate size of Al₃(Ti+X) was smaller than Al₃Ti. The third elements may decrease the lattice mistatch of Al-Al₃Ti particles by altering the dimension of the intermetallic`s unit cell and produced the smaller precipitate. The results of STEM and hardness test of as-extruded specimens exposed for 500hr. at 300℃ and 400℃ show Al₃(Ti+X) was thermally stable. Room temperature and high temperature tensile strengths at 300, 400, 500℃ of mechanically alloyed Al-Ti-X alloy were superior to those of Al-8wt.%Ti alloy, and the rate of decrease of strength with temperature was less in Al-Ti-X alloy. This improvement of tensile strength was due to the dispersion of fine Al₃(Ti+X) procipitates. |
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