Elastic constants of porous silver compacts after acid assisted consolidation at room temperature

Acid assisted consolidation (AAC) is a technique that provides elevated lev els of cohesiveness to silver powder compacts without recourse to a high te mperature treatment. Ultrasonic techniques were used to measure the elastic constants of high purity silver compacts as a function of several processi ng variables. The elastic moduli of untreated (NT) samples were found to be significantly lower than those of samples that had undergone AAC and compa cted at the same pressure. Post compaction sintering increases the elastic constants of both AAC and NT samples. The results indicate that the elastic constants are dependent not only on the density that was attained but also on the processing route that was followed. The elastic constant of a porou s metal, M, can be expressed as M = M(0)g phi, where M-0 is the elastic mod ulus of the bulk metal, g is a geometrical factor that reflects the interpa rticle contact area and phi is a quality factor that depends on the nature of the interparticle interfaces. The results suggest that sound wave veloci ty is a parameter more appropriate than density for predicting the elastic moduli of porous metallic compacts. (C) 2001 Kluwer Academic Publishers.