EARLY-TIME DYNAMICS OF WAVE-FRONTS IN DISORDERED TRIANGULAR LATTICES

The early-time behavior of transient elastic wave fronts is analyzed i n two-dimensional, randomly bond-diluted triangular lattices composed of Hooke springs. When the bond probability p similar or equal to 1, t he wave-front amplitude first oscillates and then begins to decay alge braically. This power-law decay arises from dispersion. These phenomen a should both be observable in, e.g., single cystals of fee metals. Fo r p<0.95, the amplitude decay is caused by disorder and is exponential with a decay constant alpha similar to(1-p)(1.7). There is a smooth c rossover between these two types of behaviors. [S1063-651X(98)50702-7] .