Markov Property of Continuous Dislocation Band propagation

Arnomitra Chatterjee, Variable Energy Cyclotron Centre, India,

Tensile tests were carried out by deforming polycrystalline samples of substitutional Al-2.5%Mg alloy at room temperature. The experiments were performed under fixed strain rate condition. The stress-strain curve appeared to be serrated which is commonly known as Portevin-Le Chatelier (PLC) effect. This is due to the interaction of solute atoms with the dislocations present in the material. During deformation a bunch of dislocations move coherently forming a deformation band. At sufficiently high strain rate regime these dislocation bands move continuously and is labeled as type A dislocation band. PLC effect is an example of complex metallurgical phenomenon and it is very difficult to extract the information about the system from the one dimensional time series data. Here we have analyzed the experimental time series data to reveal the underlying dynamics of type A dislocation band propagation and it appears to be a Markov process. The result is also explained from the metallurgical point of view.