(1. 湖南鐵路科技職業(yè)技術(shù)學(xué)院 機(jī)械系，株洲 412000；
2. 湖南化工職業(yè)技術(shù)學(xué)院 基礎(chǔ)科學(xué)系，株洲 412004；
3. 南昌航空大學(xué) 材料科學(xué)與工程學(xué)院，南昌330063)
摘 要: 采用機(jī)械合金化和熱壓粉末冶金工藝制備Laves相NbCr2合金試樣，應(yīng)用X射線和密度測(cè)量法研究在Laves相固溶度范圍內(nèi)(即Cr含量為61%~69%(摩爾分?jǐn)?shù)))NbCr2金屬間化合物的缺陷結(jié)構(gòu)，并對(duì)Laves相NbCr2金屬間化合物中的缺陷結(jié)構(gòu)與其力學(xué)性能的關(guān)系進(jìn)行分析。結(jié)果表明：當(dāng)Laves相NbCr2成分偏離化學(xué)計(jì)量比為33.3%Nb~66.7%Cr時(shí)，合金中存在反位置缺陷；與其它結(jié)構(gòu)的金屬間化合物不同，NbCr2的顯微硬度在化學(xué)計(jì)量處取得最大值9.41 kN/mm2，斷裂韌性在化學(xué)計(jì)量比處最小為5.55 MPa∙m1/2；隨成分偏離化學(xué)計(jì)量比，NbCr2脆性度逐漸降低，缺陷的存在對(duì)NbCr2具有韌化作用。
關(guān)鍵字: Laves相NbCr2；點(diǎn)缺陷；維氏硬度；斷裂韌性
its toughening effect
（1. Department of Mechanical Engineering, Hunan Vocational College of Railway Technology,
Zhuzhou 412000, China;
2. Department of Basic Science, Hunan Chemical Industry Vocational Technology Institute, Zhuzhou 412004, China;
3. School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, China）
Abstract:NbCr2 composite materials were prepared by mechanical alloying and hot pressing. The relationship between the defect structure and mechanical properties in the NbCr2 Laves-phase compound was discussed. The defect structures of NbCr2 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 NbCr2 Laves-phase intermetallics when its composition deviates from the stoichiometric composition (33.3%Nb−66.7%Cr). The maximum hardness of 9.41 kN/mm2 and minimum fracture toughness of 5.55 MPa∙m1/2 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 NbCr2 Laves-phase, which is contrary to the behavior of most other intermetallic compounds.
Key words: NbCr2<, /SUB> Laves-phase; point defect; Vicker hardness; fracture toughness
