An analytical electron microscopy study of the recently reported ''Ti/sub 2/Al phase'' in. gamma. Tial alloys

A variety of experimental techniques has been utilized to establish that the phase reported to be a new stable Ti/sub 2/Al phase is instead Ti/sub 2/AlN. The space group has been determined to be P6/sub 3//mmc with lattice parameters, a = 0.304 nm and c = 1.369 nm, in agreement with the results of Jeitschko, et al. Also, since this phase is observed only in alloys which do not contain ..cap alpha../sub 2/-Ti/sub 3/Al, it was suggested that the solubility of N in ..cap alpha../sub 2/ must be rather large, while that in the ..gamma..(TiAl) phase is low. In light of the improved creep properties of ..gamma.. alloys containing Ti/sub 2/AlN precipitates, it is suggested that an increase in the volume fraction of this phase, by increasing the N and/or C contents, might be used to enhance the mechanical properties of this normally brittle compound.