Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第19卷    第11期    总第128期    2009年11月

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文章编号:1004-0609(2009)11-2000-06
Laves相NbCr2金属间化合物的缺陷结构及其韧化效应
聂小武1,谢  珊2,何  燕1,鲁世强3,王克鲁3

(1. 湖南铁路科技职业技术学院 机械系,株洲 412000;
2. 湖南化工职业技术学院 基础科学系,株洲 412004;
3. 南昌航空大学 材料科学与工程学院,南昌330063
)

摘 要: 采用机械合金化和热压粉末冶金工艺制备Laves相NbCr2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))NbCr2金属间化合物的缺陷结构,并对Laves相NbCr2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NbCr2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,NbCr2的显微硬度在化学计量处取得最大值9.41 kN/mm2,断裂韧性在化学计量比处最小为5.55 MPa∙m1/2;随成分偏离化学计量比,NbCr2脆性度逐渐降低,缺陷的存在对NbCr2具有韧化作用。

 

关键字: Laves相NbCr2;点缺陷;维氏硬度;断裂韧性

Defect structure in NbCr2 Laves-phase intermetallics and
 its toughening effect
NIE Xiao-wu1, XIE Shan2, HE Yan1, LU Shi-qiang3, WANG Ke-lu3

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

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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