Abstract
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.
Highlights
Triaxial tension occurs in solids in the vicinity of some types of defects in the microstructure of crystalline solids, e.g., cracks, pores, voids, and complex phase or grain boundaries (Kelly & Macmillan, 1986)
The theoretical strength of a material is defined as the stress at which a homogeneously deformed perfect crystal becomes elastically unstable with respect to internal displacements (Clatterbuck, Chrzan, & Morris Jr, 2003)
The stable region is sensitive to the behavior of the loading mechanism and the theoretical strength is strongly depends on the direction of tension or compression since it is anisotropic
Summary
Triaxial tension occurs in solids in the vicinity of some types of defects in the microstructure of crystalline solids, e.g., cracks, pores, voids, and complex phase or grain boundaries (Kelly & Macmillan, 1986). The theoretical strength of a perfect crystal plays an important role in determining the stress distribution near the tip of a crack and is important in determining whether a material will exhibit brittle or ductile behavior (Kelly, 1966). The stable region is sensitive to the behavior of the loading mechanism and the theoretical strength is strongly depends on the direction of tension or compression since it is anisotropic. For these interesting properties, the structural and theoretical strength of solids have been widely investigated with many experimental (Fuente et al, 2002) and theoretical (Kanchana, Vaitheeswaran, & Rajagopalan, 2003) methods. Among all the theoretical methods, the Ab initio calculation based on quantum mechanics is thought to be the most precise, the complex calculations and long computation time requires higher-performance computing
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