采用机械合金化和热压粉末冶金工艺制备Laves相NbCr_2合金试样,应用X射线和密度测量法研究在Laves相固溶度范围内(即Cr含量为61%～69%(摩尔分数))NbCr_2金属间化合物的缺陷结构,并对Laves相NbCr_2金属间化合物中的缺陷结构与其力学性能的关系进行分析.结果表明:当Laves相NbCr_2成分偏离化学计量比为33.3%Nb～66.7%Cr时,合金中存在反位置缺陷;与其它结构的金属间化合物不同,NbCr_2的显微硬度在化学计量处取得最大值9.41 kN/mm~2,断裂韧性在化学计量比处最小为5.55 Mpa·m~(1/2);随成分偏离化学计量比,NbCr_2脆性度逐渐降低,缺陷的存在对NbCr_2具有韧化作用.%NbCr_2 composite materials were prepared by mechanical alloying and hot pressing. The relationship between the defect structure and mechanical properties in the NbCr_2 Laves-phase compound was discussed. The defect structures of NbCr_2 alloys in the Laves-phase solubility ranges (i.e. the Cr contents range is 61%-69% (mole fraction)) were studied by XRD and density measurement methods. The results show that the anti-site defects exist in the NbCr_2 Laves-phase intermetallics when its composition deviates from the stoichiometric composition (33.3%Nb-66.7%Cr). The maximum hardness of 9.41 kN/mm~2 and minimum fracture toughness of 5.55 Mpa·m~(1/2) occur in the stoichiometric composition, which is not similar with the behavior of most other intermetallic compounds. Meanwhile, the brittleness of the compound decreases when the composition deviates from the stoichiometry. The presence of point defects results in toughening effect in the NbCr_2 Laves-phase, which is contrary to the behavior of most other intermetallic compounds.
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