Healing cracks in materials through an electric field
Cracks in conducting or semiconducting materials could be inhibited or healed simply by applying an electric field, according to researchers at the University of Massachusetts Amherst, USA.
A computational study carried out by the group focused on the Asaro-Tiller or Grinfield instability in solids, where competing elastic strain energy and surface energy can induce extreme surface morphologies, leading to cracks. The group simulated the morphological effect of applying an electric field in a controlled manner on the stressed solid.
‘We realised there is a certain critical threshold for the strength of the electric field beyond which one can stabilise the surface, no matter how it is perturbed from the planar morphology by thermal fluctuations,’ explains Professor Dimitrios Maroudas of the University’s Chemical Engineering Department.
The electric field induces electromigration of the atoms on the surface, ‘like wind blowing on a pile of sand’, says Maroudas. This drives the atoms into any grooves, healing the cracks and inhibiting their formation.
‘What is novel here is that applying an electric current in a designed manner simultaneously with the mechanical stress will counteract the cracking effect,’ he adds.
The amount of current required depends on the stress level, as well as surface properties and mechanical loading of the material. Maroudas believes this method could be used on any electrically conducting or semi-conducting crystalline solid such as copper, aluminium or silicon.
Working with other research groups, the team hopes to see experimental validation of its findings over the next three years.