Flow and Fracture Behaviour of Tungsten Fiber Reinforced Superalloy Composites-Effect Of Specimen Geometry

Abstract

The influence of aspect ratio (i.e. width to height ratio) of test specimens on the flow and fracture behaviour of fiber reinforced composites is herein examined. The composite material was prepared by isostatic pressing of a Mar-M200 nickel-base superallov matrix reinforced with 40% tungsten wires. I. niaxial compression forging was performed at a constant true strain rate of 3x10^ S , with temperature as parameter. The aspect ratio (wo/ho) of test blanks was made to vary between 0.3 and 3, loading being always normal to the direction of wire alignment. It is herein established that peak flow stress values of composite material increase significantly with rising aspect ratio while severity of damage is shown to decrease. Furthermore, it is found that the fracture pattern is also influenced by specimen geometry. This may he attributed to some favourable effect of a hydrostatic compressive stress component which seeks to retard void formation and growth. Relevant practical implications are discussed.