Tungsten Young modulus

The mechanics of materials approach to the estimation of stiffness of a composite material has been shown to be an upper bound on the actual stiffness. Paul [3-4] compared the upper and lower bound stiffness predictions with experimental data [3-24 and 3-25] for an alloy of tungsten carbide in cobalt. Tungsten carbide (WC) has a Young s modulus of 102 X 10 psi (703 GPa) and a Poisson s ratio of. 22. Cobalt (Co) has a Young s modulus of 30x 10 psi (207 GPa) and a Poisson s ratio of. 3. 

FIGURE 1.10. Shear modulus G, bulk modulus K, Young s modulus E, and Poisson s ratio v of tungsten vs. temperature, as calculated fium single-crystal elastic constants (Gj, E, and v ) [1.31], and from measurements on polyciystalline tungsten (G, K, E, and Vj). [1.30] Taken from Metals Handbook [1.40]. o... 

Table 2.3 contains an overview of the elastic constants for some metals and ceramics. As can be seen, the anisotropy factor of tungsten is 1.0, so it is (almost) isotropic even as a single crystal. For most other materials, almost isotropic properties can only be found in a polycrystalline state. The direction dependence of Young s modulus for selected materials is plotted in figure 2.10. 

Other physical properties behave similarly to Young s modulus. If, for example, copper is used to dissipate heat from a ceramic structure, the coefficients of thermal expansion of the copper alloy and the ceramic should not differ too much to reduce thermal stresses at the interface. Adding tungsten particles to copper reduces its coefficient of thermal expansion so that it becomes closer to that of the ceramic. 

Trigonal prisms in borides, 298 Tungsten bronzes, 287 Tungsten boride, WB2, 93 Tungsten carbides, WC cobalt cutting tools, 170, 293-294 binder for BN, 233 critical load, 153 hardness, 6, 241, 302 Palmqvist cracks in, 174-175 plasticity parameter, 241 toughness, 302 Young s modulus, 241 hardness, 302... 

This is known as Hooke s law, and the constant of proportionahty E (GPa or psi) is the modulus of elasticity, or Young s modulus. For most typical metals, the magnitude of this modulus ranges between 45 GPa (6.5 X 10 psi), for magnesium, and 407 GPa (59 X 10 psi), for tungsten. Modulus of elasticity values for several metals at room temperature are presented in Table 6.1. 

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