Near-net-shape forming of Al-Al3Ni functionally graded material over eutectic melting temperature

Abstract

A possibility to make near-net-shape functionally graded material (FGM) products has been examined. The FGM billets having a graded volume fraction of Al 3 Ni in thickness direction were machined from an Al-Al 3 Ni FGM thick-walled tube manufactured by a vacuum centrifugal method. Billets, which were set in the container for the backward extruding, were heated to 650 ЊC to 680 ЊC, at which temperature the FGM becomes a mixture of molten aluminum eutectic and solid intermetallics. Then, billets were extruded successfully to FGM cups by a semisolid forming, except at 650 ЊC. Residual bulky Al 3 Ni particles are found at higher temperature. Thus, an optimum operation temperature is found to be around 660 ЊC, because bulky Al 3 Ni particles transform to fine spheroidal or fibrous shape after the forming. The volume fraction of intermetallics at the bottom region of the cup was condensed more than 60 vol pct in a proper billet setting.

Evaluation of the Rheological Behavior of a Semi-Solid Al�CSiC Composite using a Parallel-Plate Drop-Forge Viscometer

“…If the transition point is expressed as a temperature, it can range from approximately 855 K (582 ˚C) to 857 K (584 ˚C), which is just above the melting point for both materials. This conclusion is similar to those previously reported for Al-Al 3 Ni and Al-Al 3 Fe FGMs [8,9]. To ensure superior mechanical properties of the cast materials, both a moderate working duration and adequate deformation in a high-speed semi-solid forming operation is required.…”

“…To enable the visco-plastic flow analysis of near-net forming of Duralcan F3A.20S, its rheological behavior at high shear rates must be clarified. Moreover, the analysis must be meaningful to confirm the results of semi-solid forming of Al-Al-base intermetallic FGMs reported in our previously papers [8,9]. We observed that the semi-solid forming just above the melting point is adequate to obtain finer intermetallics in the Al-base FGMs.…”

“…Based on our preliminary experiments involving the backward extruding [8,9], the test temperatures were selected to fall in a range from 849 K (576 ˚C) to 863 K (590 ˚C), which ranges from less than to greater than the solidus temperatures of the matrix. The temperature was monitored using the output of a thermocouple inserted into the bottom of the container (i.e., the bottom plate) where the error was within ±2 K. The standard mass of the top plate during free-fall was 7.30 kg; a top plate with a mass of 9.37 kg was also used to allow a comparison of the effect of applied mass on the test result.…”

“…After the work of Flemings et al, a number of authors have investigated the behaviors of semi-solid materials from various viewpoints [3][4][5][6][7]. Authors have also examined near-net shape forming of Al-Al 3 Ni and Al-Al 3 Fe functionally graded materials (FGMs) at temperatures greater than the eutectic melting temperature [8,9].…”

Novel Recycling System of Aluminum and Iron Wastes-<I>in-situ</I> Al-Al<SUB>3</SUB>Fe Functionally Graded Material Manufactured by a Centrifugal Method-

“…The vacuum centrifugal method (centrifugal method under evacuated condition) 15) was applied to the alloy and a thickwalled tube with 90 mm diameter  90 mm length  15 mm thickness was manufactured. From the phase diagram of AlFe system, shown in Fig.…”