  Understanding the grain boundary deformation dynamics is very crucial to
designing materials with stable microstructures. With this quest, the
deformation behavior of coherent twin boundary under cyclic shear loading has
been studied in {\alpha}-Fe using molecular dynamics simulations to understand
the influence of strain amplitude and temperature. Twin boundary exhibited
shear coupled migration along with cyclic irreversibility character at lower
temperatures and gained almost perfect reversibility at higher temperatures of
around 1500 K. TB exhibited more sliding than migration with an increase in
temperature. The stress associated with the migration of twins was observed to
fluctuate around its average value. This was caused by layer by layer
propagation of twin boundary through the activity of 1/6 <111> = 1/12 <111> +
1/12 <111> type edge partial dislocations on "\{"112"\}" twin plane. Complete
twin reversibility and complex TB migration were noticed in the presence of
multiple parallel twin nanowires. Twin migration was observed at the larger
size nanowires with a proper combination of boundary conditions and strain
rates; otherwise, it was absent. The influence of shear strain amplitude in
offsetting the twin boundary was found to be minimal.
