清华材料科学基础课件(英文)skja_10.ppt

《清华材料科学基础课件(英文)skja_10.ppt》由会员分享，可在线阅读，更多相关《清华材料科学基础课件(英文)skja_10.ppt（24页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、材料科学基础Fundamental of MaterialsFundamental of MaterialsLesson ten2023/4/2材料科学基础3.6 Intermetallic Compounds (Intermetallic Phases)uu.Future 1.The structure of A 1.The structure of AmmB Bn n differs from those of differs from those of either A or B either A or B 2.Its composition is variable to more or

2、 less 2.Its composition is variable to more or less extension extension 3.Mixed bonding 3.Mixed bonding 4.Intermediate properties 4.Intermediate properties2023/4/22023/4/2材料科学基础材料科学基础uu.Formation AB AB The property of A The property of AmmB Bn n is between that of A and B.is between that of A and B.

3、2023/4/22023/4/2材料科学基础材料科学基础uu.Factor governing the structure of“compounds”.1)Electrochemical factor (1)Electrochemical factor (X X)2)Electron concentration (2)Electron concentration (e/ae/a)3)Size factor 3)Size factor Metal Nonmetal Metalloid Metal Nonmetal Metalloid2023/4/22023/4/2材料科学基础材料科学基础3.7

4、Normal Valence Compounds.Definition:If the number of valence electrons of the If the number of valence electrons of the cation is sufficient to complete octahedron of the cation is sufficient to complete octahedron of the anion,the compound is called the normal anion,the compound is called the norma

5、l valence compounds.valence compounds.Example:Example:CmAn meCn(8eA)sometimes:sometimes:m(eCeCC)n(8eAeAA)2023/4/22023/4/2材料科学基础材料科学基础uu.Classification according to structureaccording to structure1.NaCl and CaF1.NaCl and CaF2 2 types types NaCl:NaCl:(Mg Ca Sr Ba)(Se Te)(Mg Ca Sr Ba)(Se Te)(Mn Pb Sn)(

6、Se Te)(Mn Pb Sn)(Se Te)CaF CaF2 2:PtSn PtSn2 2 PtIn PtIn2 2 Pt Pt2 2P PAnti-CaFAnti-CaF2 2:Mg Mg2 2(Si Ge Sn Pb)Cu(Si Ge Sn Pb)Cu2 2Se LiSe Li3 3AlNAlN2 2 LiMg(N As Sb Bi)AgMgAs LiMg(N As Sb Bi)AgMgAs 2023/4/22023/4/2材料科学基础材料科学基础2.Diamond,Zinc blende,Wurtzite types2.Diamond,Zinc blende,Wurtzite type

7、s Zinc blende:Zinc blende:(Be Zn Ca Hg)(S Se Te)(Be Zn Ca Hg)(S Se Te)(Al Ga In)(P As Sb)(Al Ga In)(P As Sb)Wurtzite:Wurtzite:(Zn Cd Mn)S (Zn Cd Mn)S (Cd Mn)Se (Cd Mn)Se2023/4/22023/4/2材料科学基础材料科学基础3.NiAs structure 3.NiAs structure Example:Example:(Cr Fe Co Ni)(S Se Sb)(Cr Fe Co Ni)(S Se Sb)(Fe Co)Te

8、 (Fe Co)Te (Mn Fe Ni Pt Cn)Sn (Mn Fe Ni Pt Cn)Sn Ni(As Sb Bi)Ni(As Sb Bi)2023/4/22023/4/2材料科学基础材料科学基础Structure Normal state Ni:As=1:12023/4/22023/4/2材料科学基础材料科学基础 When Ni does not full fill octahedral interspaces Ni:As 1:12023/4/22023/4/2材料科学基础材料科学基础4.Electron Phase4.Electron Phase (Electron compound

9、s)(Electron compounds)For Alloys of IB or transition metals,and B group metals phases with sane or similar structure occur at approximately some electron concentration(e/a)these alloys are therefore called as electron compounds2023/4/22023/4/2材料科学基础材料科学基础3.8 Electron Phases (Hume-Rothery phases)Feat

10、ure:Feature:Identical on similar structure occur at Identical on similar structure occur at approximately the same electron concentration,approximately the same electron concentration,e/ae/a.2023/4/22023/4/2材料科学基础材料科学基础For example:For example:CuZn:Cu5Zn8:CuZn3:(HCP):(2+1)/2 =21/14 :21/13 :21/122023/

11、4/22023/4/2材料科学基础材料科学基础 Components Components IB or transition metal IB or transition metalmetals in B groupmetals in B group Composition range is related to Composition range is related to e/ae/a Metallic characterMetallic character2023/4/22023/4/2材料科学基础材料科学基础3.9 Size Factor Compoundsuu.Interstitia

12、l phases (Interstitial compounds)Condition A Condition A B B B:H(0.46),B(0.97),C(0.77),N(0.71)B:H(0.46),B(0.97),C(0.77),N(0.71)1.Simple interstitial compound structure1.Simple interstitial compound structureA:Transition metalsB:Interstitial elements(H,B,C,N)2023/4/22023/4/2材料科学基础材料科学基础2.2.Complex st

13、ructureComplex structure M M3 3C,(FeC,(Fe3 3C),MC),M2323C C6 6,M,M6 6C C properties of interstitial compounds properties of interstitial compounds Some metallic properties Some metallic properties Hard and brittle Hard and brittle For size factor compounds For size factor compounds2023/4/22023/4/2材料

14、科学基础材料科学基础uu.Three principles for the structure 1.space-filling principle:1.space-filling principle:Atoms tend to fill the space as closely as Atoms tend to fill the space as closely as possiblepossible 2.Symmetry principle:2.Symmetry principle:Atoms tend to build a configuration of high Atoms tend

15、to build a configuration of high symmetrysymmetry 3.Principle of multi-dimensional connection3.Principle of multi-dimensional connection2023/4/22023/4/2材料科学基础材料科学基础uu.Intermetallic compounds Examples:Examples:1.Laves phases 1.Laves phases MgCuMgCu2 2 MgZn MgZn2 2 MgNi MgNi2 22023/4/22023/4/2材料科学基础材料

16、科学基础A原子B原子2023/4/22023/4/2材料科学基础材料科学基础2023/4/22023/4/2材料科学基础材料科学基础2.2.phasephaseA Cr Mo W VA Cr Mo W VB Mn Fe Co NiB Mn Fe Co Ni3.3.Topologically close-packed phaseTopologically close-packed phase2023/4/22023/4/2材料科学基础材料科学基础Examples and Discussions2023/4/22023/4/2材料科学基础材料科学基础Exercise2023/4/22023/4/2材料科学基础材料科学基础Thank you!102023/4/22023/4/2材料科学基础材料科学基础