A composite of Fe-28Al-2Cr-1Ti (at. pct) reinforced with 20-μm diameter zirconia-toughened alumina fiber, PRD-166, was pressure cast and examined by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). A new phase, tentatively identified as Fe2AlZr, with an fcc crystal structure and a lattice parameter of 1.18 nm was occasionally found at fiber/matrix interfaces. It was proposed that the phase formed by the eutectic reaction L → Fe(Al) + Fe2AlZr. The Zr in the compound became available as a result of the dissolution of ZrO2, from the fiber into the molten alloy. The matrix contained a high density of dislocations resulting from a difference in the coefficients of thermal expansion between the matrix and fiber. It was proposed that dislocations which formed at high temperatures in either A2 or B2 states were incompatible with the low-temperature DO3 state. Geometrically necessary antiphase boundaries have been proposed to provide compatibility between dislocations formed in either the A2 or B2 states and the DO3 state.
|Original language||English (US)|
|Number of pages||9|
|Journal||Metallurgical transactions. A, Physical metallurgy and materials science|
|State||Published - 1990|
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