detwinned

Detwinned is a term used in materials science and engineering to describe a material that has undergone a process to remove internal stress or a specific orientation. This often applies to crystalline materials, particularly those that exhibit twinning. Twinning in crystals occurs when two or more crystal lattices are oriented in a symmetrical manner, typically across a mirror plane or a rotation axis. This twinning can introduce internal strains and affect the material's physical properties, such as its mechanical strength or electrical conductivity.

The detwinning process aims to eliminate these twin boundaries. This can be achieved through various methods depending on the material. Mechanical stress is a common approach, where applying a specific load can cause the twinned crystals to reorient themselves, effectively eliminating the twin structure. Thermal treatments can also be used, where heating the material to a certain temperature and then cooling it can promote the relaxation of internal stresses and the disappearance of twins. In some cases, electric or magnetic fields might also be employed to induce detwinning, especially in materials with piezoelectric or magnetostrictive properties.

Detwinning is important because it can restore or enhance the desired properties of a material. For instance, in shape memory alloys, detwinning is a crucial mechanism that allows the material to recover its original shape after deformation. By removing twins, engineers can ensure that materials perform predictably and reliably in their intended applications. The specific conditions and effectiveness of detwinning vary greatly depending on the material's composition, crystal structure, and the presence of other defects.