Virginia Tech. Department of Materials EngineeringNaval Research Laboratory (U.S.)Rao, Satish I.He, BaopingHouska, Charles R.Grabowski, Kenneth2015-05-212015-05-211991-06-15Rao, S. I., He, B. P., Houska, C. R., Grabowski, K. (1991). X‐ray diffraction analysis of concentration and residual stress gradients in nitrogen‐implanted niobium and molybdenum. Journal of Applied Physics, 69(12), 8111-8118. doi: 10.1063/1.3474610021-8979http://hdl.handle.net/10919/52408Large biaxial residual strains are developed after a 5-at.% implantation of N into Nb and Mo. The results indicate that the dominant source of internal strain arises from N located in interstitial sites. For Nb implanted at liquid-nitrogen temperature, the N atoms are located in octahedral sites. However, the data allow for some clustering as di- or tri-interstitials at the highest concentration (approximately 5 at. % N). Radiation damage is present as small vacancy and interstitial loops. Since vacancies and self-interstitials are present in nearly equal concentrations, the overall bulk dilatation cancels. However, because of their small size, a lesser core expansion has been included as a correction to the overall residual strain. Although one can obtain an estimate of the N distribution from TRIM, a more accurate description must include the distribution of knock-on energy. The latter has an important influence on the redistribution of N relative to that predicted by TRIM. Both host lattices (Nb and Mo) behave like "rigid containers" in directions parallel to the free surface and give a magnified elastic response normal to the free surface.9 pagesapplication/pdfen-USIn CopyrightNiobiumMolybdenumFree surfacesInterstitial defectsVacanciesArticle - Refereedhttp://scitation.aip.org/content/aip/journal/jap/69/12/10.1063/1.347461https://doi.org/10.1063/1.347461