高配向性ラメラ組織を有するTi-43mol%Al金属間化合物の創製とクリープ特性

Various processes consisting of high temperature deformation and heat treatment are experimentally examined on Ti-43mol%Al in order to control the lamellar arrangement in TiAl intermetallic compound. High temperature uniaxial compression in α+γ as well as α2+γ two phase state is effective to rotate the lamellar interface to the position parallel to the compression plane. The high temperature compression in α2+γ two phase state results in the formation of many cracks along the lamellar colony boundaries while no cracks are observed when the compression is made in the α+γ two phase state. Deformation in the two phase state deduce the formation of many single phase grains along the colony boundaries. It is found that the heat treatment at the temperature slightly higher than that for high temperature deformation in the α+γ two phase region is effective to eliminate the single phase grains. Compression creep tests are performed on two kinds of specimen having different lamellar arrangement; one has the lamellar interface parallel to the compression direction and the other has the interface inclined about 45° to the compression direction. The specimen having the lamellar interface parallel to the compression direction shows the creep rate much lower than that of the other.