Jpa. Lofvander et al., EVOLUTION OF A METASTABLE FCC SOLID-SOLUTION DURING SPUTTER-DEPOSITION OF TI-AL-B ALLOYS, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 202(1-2), 1995, pp. 188-192
The microstructure evolution of a nominally alpha-Ti-7Al-7B alloy synt
hesized by sputter deposition has been examined. A highly supersaturat
ed metastable single phase solid solution with a face centered cubic s
tructure was identified as being the only phase present in the as-sput
tered material. In contrast, Ti-7Al and Ti-7B alloys sputtered under t
he same conditions were also single phase but exhibited the expected h
exagonal structure of alpha-Ti. The selection of the fee phase is base
d solely on kinetics, as the thermodynamically favored phase is always
alpha (hcp). The reasons for the kinetic bias, however, are not clear
. Annealing of the Ti-7Al-7B sputtered film at 900 OC for 1 h yielded
precipitation of nano-scab TIE dispersoids in a single phase alpha-Ti
matrix. Preliminary hardness and microstructural stability results of
the dispersion unveiled promising potential for use of the physical va
por deposition technique to deposit TiB strengthened Ti-matrices on fi
bers in high-temperature metal matrix composites.