A structural aspect of alpha(alpha(2))-> lamellar alpha(2)+gamma transformation in gamma-TiAl

作者：Karadge M^*; Gouma PI

来源：Philosophical Magazine Letters, 2004, 84(7): 451-459.

DOI：10.1081/09500830410001726987

A structural mechanism for. ne lamellar microstructure formation (alpha(alpha(2)) --> alpha(2) + gamma fine lamellae) in gamma-TiAl-based as-atomized powders is discussed. The powder particles show a high density of basal stacking faults, formed by dissociation (on a basal plane) of a single 1/6[1(2) over bar 10] screw dislocation jogged at multiple locations inside an alpha - alpha(2) grain. 1/6[1(2) over bar 10] dislocations emitted from the prior alpha(alpha(2)) - alpha(alpha(2)) grain boundaries which repeatedly cross-slip from the basal plane into prismatic plane, give rise to a staircase-like stacking-fault nucleation mechanism. The basal stacking faults eventually escape from the pinning jogs and grow to form gamma lamellae. It is inferred that the thickness and distribution of gamma lamellae can be modified by controlling the jog heights and the number of dislocations emitted from the grain boundary.

• 出版日期2004-7