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Laves phase NbCr2 alloys were prepared by mechanical alloying and hot pressing sintering technology. Influences of the milling time on the grain size and density of the hot-pressed alloys were studied. The effect mechanism of grain refinement on 1100 ℃ oxidation behavior was also discussed. Results show that the relative density of the hot-pressed alloys increased and the grain size decreased when the milling time of Cr-Nb powders was prolonged. When the milling time was 100 h, the relative density and the grain size reached 98.7% and 35 nm, respectively. The grain refinement was beneficial to the improvement of Cr atom dispersion to form Cr2O3 film. However, the excessive refinement of grains resulted in the growth stress increase of the oxides film and then the oxide films cracked and shed; as a result, the oxidation was exacerbated.