The MgAl2O4 ceramics produced by the preliminary clinkering of synthesized powder was exposed to the hot isostatic pressing (HIP). Samples were subjected to a pointed impact loading, which excited the acoustical and electromagnetic emissions (AE and EME, respectively). In non-HIP-treated samples, the energy distribution in time series of AE and EME pulses followed an exponential law, while after an application of the hot isostatic pressing procedure, the emissions of both types exhibited the power law energy distributions in time sweeps. A variation of the specificity of the impact-induced AE/EME energy release was explained by a transition from the nucleation/decay of microcracks in non-HIP-treated ceramics to the self-organized dislocation folding directed to grain boundaries in the material characterized by the density that was close to that of a MgAl2O4 single crystal. Keywords: MgAl2O4 ceramics, hot isostatic pressing, impact loading, acoustic emission, electromagnetic emission.

The microcrack accumulation in impact damaged α-quartz plates prior to and after the Ar+-ion implantation was studied with the acoustical emission (AE) method. The 40 keV implantation doses of 1014 and 1016 ion/cm2 were applied. The statistical analysis of the energy distribution in impact-induced AE time series detected in unirradiated samples showed a random (poissonian type) accumulation of defects which is specific for mechanical destruction of homogeneous brittle materials. The energy distribution in the AE time series excited when damaging the preliminary implanted samples followed a power law typical for the fracture of heterogeneous solids such as rocks, ceramics, etc. The optical photography evidenced a transition from brittle (prior to implantation) to ductile damage formation caused by the disturbed interconnectivity of the crystalline structure in irradiated specimens. Keywords: ion implantation, alpha quartz, impact damaging, acoustical emission.