The article deals with issues related to the fusion of the Russian language. According to the author, it manifests itself in such morphonological phenomena as alternation of stress, alternation of phonemes and alternation of affixes. They are units of morphonology that participate in the process of synthesizing the sound image of a word in inflection and derivation of the Russian language. Stress and alternations have been described in works by prof. V.A. Redkin. An affix as a morphoneme representing variants (allomorphs) of a derivational suffix is considered in the works by S.B. Im.