The indentation depth limits for the Vickers microhardness testing of amorphous, polycrystalline, multilayer and single crystal coatings were investigated. The coating/substrate hardness ratio was varied in the range from 0.01 to 20. The critical indentation depth hc, below which the substrate has a negligible effect on the hardness, was estimated from the experimentally obtained hardness versus indentation depth curves. The results show a marked effect of the coating structure on the size of the influence zone beneath the indenter. The indentation depth limits were found to increase in the row of single crystal → polycrystalline → amorphous coatings. The obtained indentation depth criteria are compared with the reference data obtained by using finite element and kinematic calculations.
A study of radiation damage in LiF crystals under irradiation with MeV–GeV energy ions, from 12C to 238U, at temperatures varying from 8 to 300 K, depending on the ion energy, energy loss and irradiation temperature, is presented. For light ions (12C, 14N) at low fluences, it is mainly color centers that are created. Increasing the fluence leads to the overlapping of tracks and the creation of more complex color centers, defect aggregates and dislocations. For ions with an energy loss above a threshold value (dE/dx = 10 keV nm−1) the tracks exhibit a central core damage region with a radius of 1–2 nm, surrounded by an extended halo which mainly contains single color centers. In this case, ion-induced nanostructuring is observed. Novel effects of radiation damage creation under ion irradiation at 8 K are observed. The role of energy loss and irradiation temperature in damage creation is discussed.
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