The Dynamic Stress-Strain Response of High-Energy Ball Milled Aluminum Powder
Abstract
High-energy ball milling (HEBM) is a bulk powder manufacturing process used in the creation of dispersion strengthened and nanolaminate materials. Fundamentally, these materials have not been dynamically characterized in a green state prior to hot consolidation. This study incorporates porosity with these HEBM compacts to investigate the effect of high strain-rate on void collapse and particle interaction which has broad applications in development of predictive models for impact events of porous metallic structures that may be employed as energy absorbers, reactive structures, and intermetallic materials. Here, pure and HEBM aluminum powders have been characterized under dynamic compression using the split-Hopkinson pressure bar (SHPB) in a passive confinement configuration. The plastic deformation of the powder and crush up were shown to be strain-rate insensitive; and as a result, were modelled adequately with a second order P-? model. The pure aluminum and HEBM aluminum powders appear to have the same strain-hardening coefficient and strength index as solid aluminum after yielding. The powders’ respective stress-strain responses follow the same trend but differ only in strength as result of porosity and pre-strain experienced prior to dynamic compression. The HEMB powder was found to be twice as strong as the untreated pure aluminum powder.
Degree
M.S.M.E.
Advisors
Son, Purdue University.
Subject Area
Mechanical engineering|Materials science
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