Atomic-level study on the interaction of plastic slip with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">Σ</mml:mi><mml:mn>3</mml:mn><mml:mo>{</mml:mo><mml:mn>112</mml:mn><mml:mo>}</mml:mo></mml:mrow></mml:math> tilt grain boundary and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>{</mml:mo><mml:mn>112</mml:mn><mml:mo>}</mml:mo></mml:mrow></mml:math> twins in bcc metals

The $\mathrm{\ensuremath{\Sigma}}3{112}$ tilt grain boundary (GB) is found in many grains bcc polycrystalline metals due to its low energy and high stability. Moreover, it the coherent of ${112}$ twin. This paper studies interaction a pileup $1/2\ensuremath{\langle}111\ensuremath{\rangle}$ dislocations with GB, extendable twin (TB). results are applied interacting dislocation transformed into GB (or TB dislocation) that acts as source disconnections responsible for shear-coupled migration leading growth or shrinkage when interface TB. While single cannot be transmitted through interface, stress field facilitates transmission if tensile part core closer than compression part. create barriers motion crystal dislocations, strength barrier depends on crystallographic parameters. obtained slip-TB prove there no Thus, under twinning shear stress, all twins strong obstacles glide dislocations. Under antitwinnning thickness less few nanometers (5.6 nm Fe) annihilated by contributing softening, whereas thicker block propagation confine inside twin, which contributes hardening.