The relationship between the elastic modulus and porosity of sintered Fe-Cu compacts was investigated by an acoustic pulse method.
Young's and shear moduli of sintered Fe compacts and sintered Fe-Cu compacts decreased with the increasing porosity, and depended on the pore shape. The pore shape became complicated when sintering at lower temperature or for the sintered Fe-Cu compact. The complicate shaped pores decreased the Young's modulus more than the shear modulus, and then Poisson's ratio decreased. Poisson's ratio is also affected by the pore connectivity, open or closed pores, because the decreasing trend of Poisson's ratio versus the porosity of sintered compact with open and closed pores differed from that with almost open pores. The porosity, at which the closed pores change to almost open pores, in this study, was approximately 20% regardless of the type of Fe and Cu powders, Cu contents and sintering temperatures. When considering the discontinuity of elasticity versus porosity, the Young's and shear moduli and the Poisson's ratio calculated by fitting each equation against porosity, which have been derived from the sintered Fe compact, corresponded to each measured value of the sintered Fe-Cu compact.