SIMULATION OF THE GROWTH OF A BINARY COMPOSITE BY A CONTROLLED THERMAL ANNEALING

The Metropolis algorithm is used to study the evolution of the density profile of particle species in a model binary composite material on a simple cubic lattice. A specified fraction of the lattice sites are o ccupied by particles of type A and the remaining sites are occupied by particles of type B. The Hamiltonian for the system includes both nea rest-neighbor particle-particle interactions and the interaction of th e particle with a gravitational held. Particle-particle interaction st rength, gravity, and the temperature govern the hopping of each partic le in our annealing process. Variation of the planar density of the sy stem by particle type is studied as a function of annealing time, temp erature, and the volume fraction of the two components. We observe a v ariety of density distributions such as a linear density gradient with the thickness, staircase like Variation in mass distribution, and the ir combinations over the length scales which depend on these parameter s. The simulations show that a graded material with a desired density distribution can be designed by appropriately controlling the annealin g period, temperature, and the volume fraction.