First-Principles Study On Elastic Properties And Generalized Stacking Fault Energy Of Pt₃M(M=Al,Hf,Zr,Co,Y,Sc)Intermetallic Compounds

Platinum-based superalloys have excellent high-temperature mechanical properties and are widely used in high-temperature fields such as aerospace.At present,Pt-Ir and Pt-Rh are relatively mature solid solution strengthening alloy materials.However,with the rapid development of technology and industry,people have higher and higher requirements for high-temperature alloys,and the comprehensive properties of solid solution strengthened alloy materials cannot fully meet the requirements.It is necessary to develop a composite strengthened platinum-based alloy combining?/?'.Therefore,it is necessary to deeply study the basic structure and elastic mechanical properties of?'phase Pt₃M intermetallic compounds.In this paper,the first principles are used to calculate the basic structure,mechanics and thermodynamic properties of Pt₃M(M=Al,Co,Hf,Sc,Y,Zr)intermetallic compounds;the effect of pressure on the structure,mechanics and thermodynamic properties of Pt₃M intermetallic compounds;Through the generalized stacking fault energy,we focused on the deformation mechanism of Pt₃Hf intermetallic compounds,and the effects of adding trace elements of the same family(Ti,Zr)and rare earth elements(Y,Sc)on the generalized stacking fault energy and mechanical properties of Pt₃Hf intermetallic compounds.The main research contents and results are as follows:1.The basic structure,mechanical properties and thermodynamic properties of Pt₃M(M=Al,Co,Hf,Sc,Y,Zr)intermetallic compounds were studied.From Cauchy pressure,Pugh's ratio and Poisson ratio,Pt₃M intermetallic compounds show good ductility.Pt₃Hf has the highest elastic modulus(B,G,E),indicating that Pt₃Hf has the best volumetric deformation resistance,shear resistance,and strongest stiffness among Pt₃M intermetallic compounds.According to the value of the Vickers hardness,the hardness of Pt₃Hf is the highest among these six intermetallic compounds.The maximum and minimum values of the Young's modulus of the Pt₃M compound are along the<111>and<100>directions,respectively.Pt₃Co has the strongest elastic anisotropy(A^Z=1.775),while Pt₃Zr has the weakest elastic anisotropy(A^Z=1.470).According to the electronic structural properties,the metal properties of Pt₃M compounds are mainly derived from Pt-5d orbitals and M-5d orbital(or p-orbital)electrons.Electrons flow out of Pt and M atoms and accumulate to form covalent bonds,which leads to structural stability and elastic anisotropy.2.The basic structure,mechanical properties and thermodynamic properties of pressure on Pt₃M(M=Al,Co,Hf,Sc Y,Zr)compounds are studied.The elastic modulus(B,G,E)of the Pt₃M compound also showed a linear increase with increasing pressure,indicating that the volumetric deformation resistance,shear resistance and stiffness of the Pt₃M compound increased with increasing pressure.According to Poisson's ratio(?),as the pressure increases,the plasticity of Pt₃Al gradually decreases,the plasticity of Pt₃Hf and Pt₃Co decreases first and then increases,and the plasticity of Pt₃Sc and Pt₃Zr keeps increasing.The difference between the shear modulus Gmin and Gmax of the Pt₃M compound in the<110>direction is the largest,indicating that the shear deformation anisotropy is the largest in the{110}plane.As the external pressure increases,the Debye temperature of the Pt₃M compound gradually increases,indicating that the stronger the bond and the higher the thermal conductivity of the Pt₃M compound.3.Through the generalized stacking fault energy,the deformation mechanism of Pt₃Hf compound and the influence of microalloying elements(Ti,Zr,Y,Sc)on the generalized stacking fault energy and dislocation decomposition mechanism of Pt₃Hf compound were studied.The results are as follows:the total dislocation on{111}is more easily decomposed into two partial dislocations,with a reversed domain boundary in the middle,and the partial dislocations are very easily decomposed into partial dislocations with a complex stacking fault in the middle.The addition of micro-alloying elements(Ti,Zr,Y,Sc)reduces the unstable stacking fault energy along the various sliding directions of the Pt₃Hf compound{111};it does not affect the dislocation decomposition method of the Pt₃Hf compound,but lowering the kinetic energy barrier that hinders its dislocations and improving the plastic processing performance.The electronic structure analysis shows that the root of the microalloying element to improve the alloy's plasticity is that the added element reduces its atoms and the first nearest neighbors Pt and Hf atoms.The bonding strengths between.