On the influence of triple junctions on grain growth kinetics and microstructure evolution in 2D polycrystals

Grain growth in 2D microstructure is modelled under the supposition that triple junctions possess a limited mobility. The impact of the triple junctions on the grain growth kinetics is shown to depend on a dimensionless parameter Λ¯ equal to the product of the triple junction mobility and the average grain size divided by the grain boundary mobility; it was varied in the range from 0.03 to 100. With low initial Λ¯, the growth kinetics is at first linear and becomes parabolic at the later stages only. The value of the triple junction mobility estimated from the available experimental data is used to prove that an initial Λ¯ as low as 0.005 can be observed in nano-crystalline materials. Thus, the triple junction drag could explain some features of the growth kinetics in these materials.