ZrC/ZrB2 multilayers with nanoscale bilayer periods were synthesized by rf magnetron sputtering. The analysis of x-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and nanoindentation indicated that multilayers possessed much higher hardness than the rule-of-mixture value of monolithic ZrC and ZrB2 coatings. A maximum hardness (over 47 GPa) was observed in the multilayer with 27.7-nm-thick bilayer period deposited at 400 degrees C. Higher residual stress built in the ZrC layer can be released by periodic insertion of ZrB2 into ZrC layer. The enhanced mechanical properties were related to the multilayered structure with mixed ZrB2(001), ZrB2(002), and ZrC(111) orientations. (c) 2007 American Vacuum Society.