Physical and Mechanical Properties of Co3(Al,W) with the L12 Structure in Single and Polycrystalline Forms

The physical and mechanical properties of Co-3(Al,W) with the L1(2) structure have been investigated both in single and polycrystalline forms. The values of all the three independent single-crystal elastic constants and polycrystalline elastic constants of Co-3(Al,W) experimentally determined by resonance ultrasound spectroscopy at liquid helium temperature are 15 similar to 25% larger than those of Ni-3(Al,Ta) but are considerably smaller than those previously calculated. When judged from the values of Poisson's ratio, Cauchy pressure and G(h) (shear modulus)/B-h (bulk modulus), the ductility of Co-3(Al,W) is expected to be sufficiently high. Indeed, the value of tensile elongation obtained in air is as large as 28 %, which is far larger than that obtained in Ni3Al polycrystals under similar conditions.