NiAl Intermetallic Compound B,P Alloying Calculated With First-principles Calculations

B2-NiAl intermetallic compound has many merits such as high melting point,low density,good thermal conductivity and good high temperature oxidationresistance,so it is seen as an ideal aerospace structural material to substitutes theNi-based alloys,but the NiAl material’s application is restricted by its poor ductility atroom temperature. Domestic and foreign researchers have done much work to reducethe brittleness by adding alloy elements and graining refinement. The paper selectedthe NiAl alloy as the research object,using the first-principles plane-wavepseudopotential method obtains the NiAl’s microphysics characteristic and electronicstructure information. Based on virtual crystal approximation (VCA), calculate andanalysis P alloying element affection to the NiAl alloy’s mechanical properties. Basedon the electronic mechanism’s analysis,discusses the theory of alloy enhance NiAl’smechanical properties.Calculated the NiAl system’s lattice constant, heat formation, electronic densityof states and the energy band in this paper.The result of lattice constant,heat formation,electronic density of states and elastic constant calculated in this paper are consistentwith the experimental values and other calculated values.Calculated the B element site substitution in NiAl alloy.The crystal structureoptimization results show that B occupy the tetrahedral gap of γ position afterstructure optimized, it went to octahedral gap of α position, the B atom more likelyoccupy smaller octahedral gap. With all the three positions B element occupied,theformation heat and binding energy is very close.Considering the charge number,electric-charge density, the amount of lattice distortion and crystal structure ofoptimization results, B atoms more likely to occupy the octahedral gap α position.And further discussed the B elements influence on electronic structure andmechanical properties. The elastic modulus results show that: while adding Belements to NiAl will reduce the hardness and improve the ductility.Calculated and analyzed the five position P mixed into B2-NiAl intermetalliccompound. From the energy analysis results, we can see that P atoms are less likely tooccupy the three gap position, instead P replace Ni or Al atom are more possible.From the lattice distortion quantity analysis results, we can see that P replace Ni or Alatom have lower energy, and the system tend to be stable. Calculated and analyzed the influence of different P’s thickness alloying B2-NiAlintermetallic compound, the results show that when P micro alloying’s thicknessaround x=0.125%,B2-NiAl crystal have the best ductility. When P micro alloying’sthickness around x=0.188%, B2-NiAl crystal’s solid solution strengthening hardnessare increasing rapidly,but the ductility drops.When P micro alloying’s thicknessaround x=1.25%and x=3.75%-6.25%interval,B2-NiAl crystal ductility have animprovement. While around x=0.5%,B2-NiAl crystal have the worst ductility.