Experimentally-based Micromechanical Modeling of Dynamic Response of Molybdenum

Molybdenum (Mo), a bcc metal with a melting point of 2,610°C and a density of 10.22 g/cm, is an important refractory metal. The refractory properties of molybdenum reflect the high strength of interatomic bonding resulting from the overlap of the 4d-orbitals and the number of bonding electrons available (1). The melting point of molybdenum is exceeded only by those of tungsten and tantalum, among the useful high-temperature metals. This makes molybdenum essentially a “hot strength” material. Molybdenum is ductile at room temperature, with a brittle-ductile transition temperature significantly lower than that of tungsten. The density of molybdenum is approximately 62% of that of tantalum, and is approximately one half of that of tungsten, making molybdenum a good candidate for applications where high-temperature capability, weight considerations, and ductility are key issues. Molybdenum also possesses much greater specific heat than either tantalum or tungsten, making it easier to thermally treat molybdenum to produce structures with low thermal stresses than most other metals. Molybdenum is resistant to most chemical reagents except for oxidizing acids. The relatively low thermal neutron cross section of molybdenum also makes it suitable for nuclear applications. The unique properties of molybdenum make it an ideal material for high-temperature engineering applications. Since the 1960’s, molybdenum has also been chosen by many researchers as an ideal material to examine the deformation behavior of bcc metals. These studies have, however, focused on low strain-rate regimes. The deformation characteristics of bcc metals differ markedly from those exhibited by fcc metals. For example: