Composition and lattice parameters of silicide and matrix in cast Ti–Si–Al–Zr alloys

Abstract

The silicide chemistry, i.e. the type, composition, and lattice parameters of the silicide in as cast titanium based Ti–Si–Al–Zr alloys, has been studied. It has been shown that the stoichiometry of the silicide in the alloys can be expressed as (Ti_1−x, Zr_x)₅(Si_l−y, Al_y) _{2·76−3·04}(0≤X< 0·2, 0≤y<0·1). The presence of Al and Zr in the silicide increases its lattice parameters. Addition of Al coarsens the eutectic silicide and slows the formation of secondary silicide precipitates by solid state reaction. Addition of zirconium refines the eutectic silicide and promotes secondary silicide precipitation. The silirides are low in Al and rich in Zr, whereas the Ti matrix is rich in Al and low in Zr. The lattice parameters of the Ti matrix are decreased by Al and increased by Zr.

MST/1427