Fabrication and mechanical properties of porous Co-Cr-Mo alloy compacts without Ni addition

Abstract

Porous Co-29Cr-6Mo (mass%) compacts without Ni were fabricated by hot pressing and their microstructure and mechanical properties were investigated. PREPed Co-29Mo-6Mo powder with a diameter range (300-500 μm) was hot-pressed under the uniaxial pressure of 40 MPa at 1223 K for 7.2 ks. Hot-pressed compacts were annealed at 1473 K for 7.2 ks for further sintering. X-ray diffraction analysis revealed that γ and ε phases appeared dominantly in the PREPed powder, while ε and σ phases coexisted in the compact which was hot-pressed at 1223 K. After annealing at 1473 K. only the K phase was detected although the γ phase was stable at this temperature. Therefore, the ε phase formed during furnace cooling. Tensile behavior of porous Co-29Cr-6Mo compacts was characterized by the stress-strain curves. The as-hot pressed compact showed linear deformation followed by sudden fracture. The annealed compact showed higher ultimate tensile strength (UTS) and lower yield strength than the as-hot pressed compact. Young's modulus of the annealed compact was difficult to determine from the stress-strain curve. However, the annealed compact possessed a tensile strength of 116 MPa, which is comparable to that of human cortical bone. 2006 The Japan Institute of Metals.