S. Sankaran

Influence of TiB2 Addition on the Precipitation Kinetics in Al-7Si-0.3Mg In Situ TiB2 Composites

Precipitation behavior of the Al-7Si-0.3Mg/TiB2in situ composites was investigated using differential scanning calorimetry and transmission electron microscopy, and it was found that Si precipitation is accelerated with increase in TiB2 content. Non-isothermal kinetic analysis clearly showed a decrease in the precipitation kinetics of the overaged metastable precipitates in the Mg2Si precipitation sequence.

First Steps of Crack Initiation and Propagation in Fatigue of FCC Crystals Studied by Dislocation Dynamics

3D discrete dislocation dynamic (DDD) simulations are performed to simulate stage-I fatigue crack initiation and propagation along the surface, in the primary grain and its neighbouring grain, in 316L stainless steel. The scenario of crack propagation in primary grain and the evolution of dislocation structure ahead of crack tip are discussed, and in addition crack tip sliding displacement is estimated. Probable mechanisms of crack propagation from primary grain to neighbouring grain are evaluated. In this process, surface relief in the neighbouring-grain under the influence of crack stress field in the primary grain is studied for varying neighbouring-grain orientations. An enhanced evolution of surface extrusions in the neighbouring grain, are observed in the presence of heterogeneous stress field (i.e., in the presence of crack in the primary grain), compared to that in the case of homogeneous stress field. In addition, influence of crack stress field on prior cyclic-deformed substructure is presented.Copyright