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First principle calculations using supercell approach and coherent potential approximation (CPA) are performed to investigate the electronic and magnetic structures of Fe3−xMnxSi and Fe3−yMnSiy alloys, where x,y=0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.5, 1.75, and 2.25. Using supercell calculations we obtained a metallic behavior for x=0, 0.25, and 0.5 in Fe3−xMnxSi alloys with spin polarizations of 24%, 39%, and 93%, respectively. The behavior starts to be half-metallic at x=0.75 with a small direct band gap that increases for higher concentrations of Mn. Among the half-metallic systems, only those of L21 structure at x=1 and 2 possess indirect band gaps along Γ-X symmetry line. The change of Si concentration in Fe3−yMnSiy structures retrieve the metallic behavior for all concentrations except y=1.25 that shows a half-metallic behavior with a direct band gap of 0.27 eV. We obtained a good agreement between supercell and CPA calculations for the values of the magnetic moment and the trends of the formation ene...

The alloying effects of Nb, Zr, and/or Sn on the phase stability and elastic properties of Ti are investigated by using a first-principles method. Our calculation results indicate that a carefully designed Ti-Nb-Zr-Sn system can be a good candidate for low modulus biomedical materials. We find that the well-known correlation between the e/a ratio and both elastic and phase stabilities for Ti alloyed with transition metal elements breaks down for the Ti-Sn alloy.

Most of the engineering materials are alloys (solid solutions) and inevitably contain some impurities or defects such as vacancies. However, theoretical predictions of the hardness of this kind of ...

We introduce a hardness formula for the multicomponent covalent and ionic solid solutions. This expression is tested on nitride spinel materials A(3)N(4) (A=C,Si,Ge) and applied to titanium nitrogen carbide (TiN(1-x)C(x) with 0

Here we report a non-toxic β-type titanium alloy exhibiting unstable elastic and plastic deformation behavior. Elastic instability leads to remarkable elastic softening, i.e., the decrease of incipient Young’s modulus with slight pre-straining. In spite of partial recovery during room-temperature aging, a stable modulus of 33GPa matching that of human bone can be maintained. Plastic instability causes highly-localized deformation which is very effective in grain refinement but contributes little to strength. We thus obtain soft nanostructured metallic materials (NMMs): The flow stress increases by only ∼5.5% as coarse grains are reduced to below 50nm, in contrast with several times increase for previously-reported NMMs.