<title>Residual stress measurements on polycrystalline diamond</title>

The magnitude of the residual stresses in thick samples of polycrystalline diamond were measured by the sine squared, angular resolved x-ray diffraction (XRD) technique and by detailed analysis of electron channeling patterns from individual grains in polished diamond films using a scanning electron microscope. The XRD measurements were made on samples produced by both plasma torch and microwave plasma low pressure growth techniques with a range of microstructures. Results show that residual levels of stress +/- 0.3 GPa can be generated inside the thinner films on substrates by thermal expansion mismatches, while average residual stress in free standing 0.5 to 2 mm thick diamond plates is negligible. Within the individual grains of the thicker films, localized stress variations on the order of +/- 0.5 to 0.8 GPa can be distinguished.