Rights: © 1994 American Physical Society (APS). This is the accepted version of the following article: Puska, Martti J. & Sob, M. & Brauer, G. & Korhonen, T. 1994. First-principles calculation of positron lifetimes and affinities in perfect and imperfect transition-metal carbides and nitrides. Physical Review B. Volume 49, Issue 16. 10947-10957. ISSN 1550-235X (electronic). DOI: 10.1103/physrev...