Quasi-isostatic, Solid-State Forging of a Nanophase Aluminum Alloy for Rocket Turbopump Components

Research to establish the potential performance benefits of nanocrystalline engineered materials (grain size less than 100 nanometers) gained momentum in the mid-1990¿¿s (1). Significant effort has since been focused on the areas of powder preparation,powder consolidation, microstructure evolution and control, and product fabrication technologies.Powder consolidation has been achieved primarily by hot isostatic pressing (HIP) which is governed by diffusion mechanics and requires exposure of the nano-powders to a temperature of (315,a C) for extended periods of time (3 hours). The process isexpensive and can easily result in a loss of nanocrystallinity due to rapid and unpredictable grain growth. Low (15 ksi/104 MPa) isostatic pressures are unable to break-up tenacious powder surface oxides thus requiring extensive secondary deformationprocessing to obtain usable material.The Ceracon,¿ Powder Forging Technology uses a conventional hydraulic forging press, and is a cost effective, near-net-shape alternative to HIP. High uniaxial ram pressure (127 ksi/876 MPa) is transformed into a quasi-isostatic pressure field through theuse of a granular ¿pressure transmitting media¿