A First-principles Study Of Generalized Stacking Fault Energy In Mo Alloys

Having study the metals Mo, W, Fe and Ta, the generalized-stacking-fault energies along the direction [111] on the (110) plane, Having doped the transition metals W, Ti, Cu and Fe with the molar percentage of2.08%and4.17%in Mo and having doped the rare metal La, Ce with the molar percentage of2.08%in Mo, the generalized-stacking-fault energies and the cleavage energies along the direction [111] on the (110) plane have been calculated by the first principle method based on the density functional theory, and the shear information and the brittle-ductile influences of the transition metals to the Mo material have been investigated. Resulting in generalized stacking fault energy as the main theoretical basis to measure the impact of each metal and alloying elements on the microscopic deformation mechanism of the system, and finally from the perspective of the crystal structure and electronic properties to clarify the reason.(1) Calculated molybdenum, tungsten, iron, tantalum in different pseudopotential (LDA, GGA-PW91, PBE) generalized-stacking-fault energy point of view, It is a big impact. From the perspective of pseudopotential to consider, description the premise of mainly in the energy calculation, the PW91 calculated value is less than LDA and PBE calculated value; Considered from the perspective of a crystal model, we found that the value of PW91calculated total energy is always better than using other pseudopotential calculated value is smaller, indicates that the PW91is more inclined to calculate interface or the surface of the problem; From the perspective of the element type, PW91more suitable transition metals. On the one hand, we can see be calculated from the results of the generalized stacking fault, On the other hand we know that the transition metal is a high-density system, In calculating this type of system, the exchange can play a leading role, Its PW91nonlocality better suited to handle the density of non-uniformity.(2) Having doped the transition metals W, Ti, Cu and Fe with the molar percentage of2.08%and4.17%in Mo, doping atoms of W and Ti can make the shear deformation become difficult and can enhance the brittleness of Mo, however, the doping atoms of Cu and Fe can make the shear deformation become easy and can enhance the ductility of Mo. Moreover, with the increment of doping concentration, the influences of W and Fe are more obvious with that, the doping atom of W can make the shear deformation become more difficult and can make the brittleness of Mo become more stronger and the doping atom of Fe can make the shear deformation become easier and can make the ductility of Mo become more stronger.(3) Having doped the transition metals La and Ce with the molar percentage of2.08%in Mo, the doping atoms of La, Ce can make the shear deformation become easy and can enhance the ductility of Mo. But relatively speaking, this phenomenon will become more apparent after doping La atoms.