Structure and mechanical properties of pure iron 0.8–2.0-mm thick condensates in tension are studied as a function of the substrate temperature within the range 270 °–860 °C. The mechanical properties of two-phase Fe–NbC condensates, containing up to 18% by volume niobium carbide were investigated at room temperature and 700 °C. The introduction of niobium carbide, having negligible solubility in iron, into the latter permits one to increase the tensile and yield strengths of condensates up to 90 and 86 kg∕mm2, respectively, at room temperature, and tensile and yield strengths of 45 and 36 kg∕mm2 at 700 °C with 13%–16% by volume NbC content. The effect of alloying the iron matrix with nickel in the amount of 18% by weight on the structure and mechanical properties in tension of Fe–Ni–NbC material was determined. The tensile and yield strengths of such materials reached 116 and 108 kg∕mm2, respectively, at 20 °C and 59 and 40 kg∕mm2 at 700 °C where the NbC content was approximately 9% by volume. An attempt was made to evaluate the increment of yield strength when introducing NbC-dispersed particles from the stand point of Orowan and Ansell–Lenel theories. It has been found that the contribution of the dispersed particles and solid solution into the condensate, strengthening at room temperature, is governed by the law of additivity.