THE EFFECT OF DENSITY ANISOTROPY ON THE YIELDING AND FLOW BEHAVIOR OFPARTIALLY CONSOLIDATED POWDER COMPACTS

The effect of density anisotropy on the flow behavior of partially con solidated powder compacts of an alpha-two titanium aluminide alloy (Ti -24Al-11Nb) was established by conducting hot compression tests on sam ples made by hot die pressing or hot isostatic pressing (''hipping''). For the former consolidation method, in which anisotropic density dis tributions were developed, the upset tests were conducted both paralle l and perpendicular to the die pressing direction. The flow stress res ults from these experiments, as well as those from the tests on the '' hipped'' material, were interpreted in terms of calculations of the st ress intensification factor (phi). When the stress intensification fac tors were plotted as a function of areal relative density, rather than volumetric relative density, a unique dependence of phi on density wa s obtained. This dependence showed a smooth transition from a behavior measured by others for the early stages of densification to a behavio r theoretically predicted for the latter stages of densification, in w hich isolated pores are closed.