First-principles Study Of The Mechanical Properties Of B2 Structure Of Metal Compounds

In the first chapter, the application and restriction of NiTi,NiAl are reviewed . In chapter 2, the basic idea and concept of density functional theory (DFT) is introduced. In the following two chapters, our calculated results for the mechanical property of NiTi,NiAl,Ni2TiAl and ideal tensile strength of FeTi,CoTi,NiTi are described and discussed respectively.On one side, we investigate the mechanical property of NiTi,NiAl,Ni2TiAl from first principles .We judge rigidity and ductibility by elastic constant. Our calculated results indicate the rigidity from strong to feebleness in turn is NiAl,Ni2TiAl,NiTi , the ductibility is on the contrary ,the reason for this phenomena is that the directivity of Ni atom and Ti atom bonding is more feebleness than the directivity of Ni atom and Al atom bonding .On the other side, we study the ideal tensile strength of FeTi,CoTi,NiTi from first principles . Our calculated results indicate that the rigidity and stability from strong to feebleness in turn is FeTi,CoTi,NiTi , and the martensitic transformation is prone to B2-to-B19ˊtransformation ,and the ideal tensile strength of FeTi,CoTi,NiTi along (001)direction 28GPa, 22Gpa,2.1Gpa respectively.