Explosive consolidation of rapidly solidified aluminum alloy powders
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I.
INTRODUCTION
EXPLOSIVE compaction of rapidly solidified alloy powders is attractive because the processing time is short, usually milliseconds, and the bulk of the compact remains at low temperature, thus retaining the inherent benefits of rapid solidification such as fine grain size, uniform distribution of fine dispersoids, and supersaturated solid solutions. For aluminum alloys, explosive compaction can also provide improved interparticle bonding compared with conventional processing by fragmenting and dispersing the unavoidable oxide film on the powder particle surfaces. Previous investigations of aluminum-alloy-powder dynamic consolidation using explosives or projectiles 1-6 have reported 95 to 100 pct densification. However, poor interparticle bonding and various crack patterns remain major problems in achieving practical product forms and sizes. The results presented here on the explosive compaction of an A1-Cu-Li-Mg alloy show that these problems can be systematically reduced and likely solved.
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II.
EXPERIMENTAL PROCEDURE
Rapidly solidified A1-4.6Cu- 1.1Li-0.56Mg-0.52Fe0.13Zr alloy powders were used in this study. The powders were produced by vacuum atomization by Homogeneous Metals, Herkimer, NY. The powders were stored under dry argon from the time they were prepared until they were used for these experiments. The powders were packed in a 3.2-cm-diameter, 14-cm-long, mild-steel cylinder for consolidation, as shown in Figure 1. The packing sequence consisted of evacuating the cylinder and vibrating the powder for 20 to 75 hours, and cold pressing the powder to 57 to 66 pct of theoretical density (2.74 g/cm3). A 0.64-cm -diameter 2024 Al-alloy core rod was used to reflect the inward compression wave into an outward compression wave and avoid radial cracks in the compact. The experimental arrangement used for explosive compaction is illustrated in Figure 2. The explosive parameters T.C. PENG and J.E. O'NEAL, Scientists, and S . M . L . SASTRY, Senior Scientist, are with McDonnell Douglas Research Laboratories, P.O. Box 515, St. Louis, MO 63166. D. BRASHER is Engineer, Northwest Technical Industries, Sequim, WA. Manuscript submitted November 5, 1984. METALLURGICAL TRANSACTIONS A
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Dimensions in millimeters Fig. 1 - - A s s e m b l e d alumiaum-alloy powder pack ready for explosive consolidation. VOLUME lbA. AUGUST 1985-- 1445
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Table. I Powder Parameters, Explosive Parameters, and Consolidate Properties of Explosive Consolidations Powder Pack
Specimen Number
Size Distribution
1 2 3 4 5
Packing Density (Pet Theoretical)
as in Table II 62.6 as in
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