Comparison of Absorption and Desorption of Cryomill Process Control Agents and Their Effect on Compressive Behavior of Trimodal Aluminum Metal-Matrix-Composites

Report No. ARL-TR-6808
Authors: Anit Giri; Clara Hofmeister; Sarah Brennan; Tim Delahanty; Yongho Sohn; Kyu Cho
Date/Pages: February 2014; 20 pages
Abstract: Aluminum composite (AA5083) and boron carbide (B4C) powders were cryomilled in liquid nitrogen using different process control agents (PCAs) such as oleic acid, caprylic acid, and stearic acid individually in order to determine the effect of each PCA on the resultant microstructure and mechanical properties. The microstructure of the powders was examined and consolidated samples were mechanically tested in compression. Chemical analysis was performed to determine impurity concentrations of nitrogen, hydrogen, and oxygen. Microstructural analysis of the powders revealed three types of agglomerates: composite powders of AA5083 with uniformly distributed B4C particulate, unmilled spherical AA5083 powder and deformed AA5083 powder. These three types of agglomerates were found in similar size and proportion regardless of the PCA used. Correlation among PCA type, impurity concentrations, microstructure, and mechanical properties were examined.
Distribution: Approved for public release
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Last Update / Reviewed: February 1, 2014