Structure and Stability of BCC Crystals Fe, V, Nb and Ta under Hydrostatic Loading

The structural stability and theoretical strength of BCC crystals Fe, V, Nb and Ta under hydrostatic loading have been investigated by using the modified analytical embedded atom method (MAEAM). For all the calculated BCC crystals, the failures occur while the relation m >0 is violated in compression and k >0 is violated in tension. It found that the stable regions are 0.9269~1.1495, 0.9270~1.1545, 0.9268~1.1449 and 0.9268 ~ 1.1427 in the lattice stretch l or the corresponding -408.89 ~ 123.54, -186.96 ~ 131.43, -259.07 ~ 152.53 and -283.92 ~137.04eV/nm3 in the theoretical strength for Fe, V, Nb and Ta, respectively. The calculated maximum tensile stresses smax of Fe, V, Nb and Ta are 123.57, 131.74, 154.45 and 137.85eV/nm3 and the corresponding lattice stretch lmax ??are 1.1527, 1.1617, 1.1661 and 1.1545. The calculated maximum tensile stress smax and the corresponding lattice stretch lmax ??of Fe are consistent well with the results of Ab initio calculation.