RT Journal Article ID 3754fcf30a9f1235 A1 Tomar, Vikas A1 Samvedi, Vikas T1 Atomistic Simulations - Based Understanding of the Mechanism behind the Role of Second-Phase SiC Particles in Fracture Resistance of SiC-Si3N4 Nanocomposites JF International Journal for Multiscale Computational Engineering JO JMC YR 2009 FD 2009-09-01 VO 7 IS 4 SP 277 OP 294 K1 nanocomposites K1 molecular dynamics K1 dynamic fracture AB One of the primary factors affecting the failure in high strength Silicon Carbide (SiC)-Silicon Nitride (Si3N4) nanocomposites is the placement of spherical nano-sized SiC particles in micro-sized Si3N4 grains. It has been found that as a result of a significant number of nanosized SiC particles being present in micro-sized Si3N4 grains, the SiC particles invariantly fall in wake regions of microcracks leading to significant structural strength. In this research, this mechanism is examined using 3-D molecular dynamics (MD) simulations of crack propagation in SiC-Si3N4 nanocomposites with cylindrical SiC inclusions. Analyses reveal that the second phase particles act as significant stress raisers bringing down the internal strength of the single crystal and bi-crystalline Si3N4 blocks by a factor of almost 2 times. With smaller SiC particle, the interfacial boundary in the bi-crystalline Si3N4 block acts as a stress reliever. However, with increase in the size of SiC particle and with decrease in the spacing between adjacent SiC particles the interfacial boundary's presence results in significant internal stress rise. The results point out that the placement of SiC particles along the interfacial boundaries will not always lead to strengthening of the nanocomposite. Overall, MD analyses confirm the earlier continuum simulation and experimental results concerning the effect of second phase SiC particles on the SiC-Si3N4 nanocomposite strength. In addition, MD analyses also point out that the strengthening of the nanocomposite by placing second phase particles along grain boundaries is only possible for a selective few second phase particle sizes. PB Begell House LK https://www.dl.begellhouse.com/journals/61fd1b191cf7e96f,232871fc3b0df9a5,3754fcf30a9f1235.html