Electron and optical electron microscopy, together with energy dispersive X-ray (EDX) chemical microanalysis, were employed to examine the microstructure of a pressure-cast composite consisting of a Ti-48.4 at. pct Al-1 at. pct Mn matrix reinforced with DuPont's PRD-166 A12O3 fibers containing 20 wt pct partially stabilized ZrO2. The originally cylindrical fibers were found to have a scalloped surface, and a zone just below the surface was free of ZrO2. In addition, the fibers contained entrapped TiAl, and a small portion of the fiber periphery was covered by ZrO2 particles, which were free of the Y2O3 and HfO2 oxides present in the ZrO2 within the fibers. The matrix consisted of a mixture of TiAl and a lamellar structure of TiAl and Ti3Al and contained Zr not originally present in the matrix alloy. An analysis of the origin of this microstructure is presented.
ASJC Scopus subject areas