ULTRASONIC EVALUATION OF ELASTIC PARAMETERS OF SINTERED POWDER COMPACTS

The variation of elastic moduli, M, of sintered powder compacts with p orosity, p, has been analysed in terms of an equation M = M(o) (1-p)n, where M(o) is the elastic modulus of non-porous material and n is a c onstant. The variation of ultrasonic velocities has also been describe d in terms of a similar equation derived from the relations given by p hysical acoustics theory. It has been shown that the parameter n is re lated to a stress concentration factor around pores in the material an d is dependent on pore geometry and its orientation in the material. T he observed variation in moduli and velocities with porosity has been compared with the theoretically predicted values based on self-consist ent oblate spheroidal theory.