The interactions of 1/6<112]{111}γ slip dislocations in deformation twins with {111}γ/(00•1)α2 interphase interfaces, intersecting along both <101]γ (30°-type) and <110]γ (edge-type) directions, in duplex alloys after tensile room-temperature deformation, were investigated by means of transmission electron microscopy. The dislocation reactions which were involved in each of these types of interaction were identified by matching experimental and computed images. Slip transfer of 30°-type 1/6<112]{111}γ twinning dislocations across the γ/α2 interface into 1/3<1¯1•0>{11•0}α2 slip dislocations was confirmed, and was completely characterized. A new secondary slip system of 1/3<11•0>{3¯3•1}α2 was activated within the α2 phase under high levels of plastic strain. This new slip system was also observed to be the favoured route for slip-transfer of incoming 30°-type 1/6<112]{111}γ twinning dislocations when the plane of the γ/α2 interface deviated significantly from {111}γ/(00•1)α2 and the line of intersection was no longer close to <101]γ. For interactions which involved edge-type 1/6<112]{111}γ twinning dislocations with {111}γ/(00•1)α2 γ/α2 interfaces, no significant transfer of dislocations into the α2 phase was observed. Instead, stress relief of incoming twinning-dislocation pile-ups at the γ/α2 interfaces occurred via ½<110]{001)γ slip dislocations which were 'reflected' back into the γ phase; together with the generation of a new twinned γ grain at the γ/α2 interface. No dislocation reactions which involved c-component dislocations in the α2 phase were observed for any of the investigated interactions.

Slip Transfer of Deformation Twins in Duplex γ-Based Ti-Al Alloys - II. Transfer across γ-α2 Interfaces. C.T.Forwood, M.A.Gibson: Philosophical Magazine A, 2000, 80[12], 2785-811