Near β titanium alloy Ti–5Al–5Mo–5V–3Cr–1Zr with acicular α microstructure was hot compressed at 750°C/10−3 s−1. Twinning and its effect on the evolution of acicular α were investigated. Twinning is induced from the dislocations pile-up at α/β boundary. The twinning system is . During twinning, one type of pure shear displacement and three types of shuffle + shear mixed displacement are confirmed. The twinning dislocation can be expressed as (b, 4h0), , h0 is the interplanar distance of , , κ = c/a. Substructures form in acicular α through the migration of twin boundary, followed by meeting another neighbouring parallel twin and then causing the twins-merging. And the accumulation of the twinning displacement results in the bending of acicular α.
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. During twinning, one type of pure shear displacement and three types of shuffle + shear mixed displacement are confirmed. The twinning dislocation can be expressed as (
, h0 is the interplanar distance of 
, 
, κ = c/a. Substructures form in acicular α through the migration of twin boundary, followed by meeting another neighbouring parallel twin and then causing the twins-merging. And the accumulation of the twinning displacement results in the bending of acicular α.
edge dislocation under applied shear stresses in an h.c.p. model crystal
and 
planes in hexagonal close-packed crystals